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https://github.com/holub/mame
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sound/dac76.cpp: Emulating multiplying capability. (#13577)
* Added support for reference current (multiplying capability). * Added support for voltage output. * Added support for streaming reference current. * Used those capabilities in oberheim/dmx.cpp and linn/linndrum.cpp.
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m1macrophage
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@ -38,12 +38,38 @@ dac76_device::dac76_device(const machine_config &mconfig, const char *tag, devic
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device_t(mconfig, DAC76, tag, owner, clock),
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device_sound_interface(mconfig, *this),
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m_stream(nullptr),
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m_streaming_iref(false),
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m_voltage_output(false),
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m_r_pos(1.0F),
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m_r_neg(1.0F),
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m_chord(0),
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m_step(0),
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m_sb(false)
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m_sb(false),
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m_fixed_iref(1.0F)
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{
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}
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void dac76_device::configure_streaming_iref(bool streaming_iref)
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{
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m_streaming_iref = streaming_iref;
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}
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void dac76_device::configure_voltage_output(float i2v_r_pos, float i2v_r_neg)
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{
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m_voltage_output = true;
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m_r_pos = i2v_r_pos;
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m_r_neg = i2v_r_neg;
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}
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void dac76_device::set_fixed_iref(float iref)
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{
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if (m_fixed_iref == iref)
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return;
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if (m_stream != nullptr)
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m_stream->update();
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m_fixed_iref = iref;
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}
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//-------------------------------------------------
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// device_start - device-specific startup
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//-------------------------------------------------
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@ -51,12 +77,14 @@ dac76_device::dac76_device(const machine_config &mconfig, const char *tag, devic
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void dac76_device::device_start()
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{
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// create sound stream
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m_stream = stream_alloc(0, 1, machine().sample_rate() * 8);
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const int input_count = m_streaming_iref ? 1 : 0;
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m_stream = stream_alloc(input_count, 1, machine().sample_rate() * 8);
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// register for save states
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save_item(NAME(m_chord));
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save_item(NAME(m_step));
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save_item(NAME(m_sb));
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save_item(NAME(m_fixed_iref));
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}
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//-------------------------------------------------
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@ -85,5 +113,24 @@ void dac76_device::sound_stream_update(sound_stream &stream, std::vector<read_st
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vout *= (m_sb ? +1 : -1);
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// range is 0-8031, normalize to 0-1 range
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outputs[0].fill(stream_buffer::sample_t(vout) * (1.0 / 8031.0));
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stream_buffer::sample_t y = stream_buffer::sample_t(vout) * (1.0 / 8031.0);
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if (m_voltage_output)
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{
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static constexpr const float FULL_SCALE_MULT = 3.8F; // From datasheet.
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y *= ((y >= 0) ? m_r_pos : m_r_neg) * FULL_SCALE_MULT;
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}
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write_stream_view &out = outputs[0];
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if (m_streaming_iref)
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{
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const read_stream_view &iref = inputs[0];
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const int n = out.samples();
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for (int i = 0; i < n; ++i)
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out.put(i, iref.get(i) * y);
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}
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else
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{
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out.fill(m_fixed_iref * y);
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}
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}
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@ -4,7 +4,7 @@
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PMI DAC-76 COMDAC
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Companding D/A Converter
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Companding Multiplying D/A Converter
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Equivalent to the AM6070, which is an "improved pin-for-pin replacement for
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DAC-76" (according to the AM6070 datasheet).
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@ -20,6 +20,19 @@
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B6 8 | | 11 VR+
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B7 9 |_______| 10 VLC
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Given:
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- Iref = current flowing into VR+
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- X = DAC value, normalized to [-1, 1]
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- E/D (pin 1) is low
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The output will be:
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- IOD+ = (X > 0) ? (3.8 * Iref * abs(X)) : 0
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- IOD- = (X < 0) ? (3.8 * Iref * abs(X)) : 0
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The outputs are typically converted to voltages and summed into a single
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signal by a current-to-voltage converter (I2V) consisting of an op-amp and
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two resistors.
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***************************************************************************/
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#ifndef MAME_SOUND_DAC76_H
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@ -39,6 +52,25 @@ public:
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// construction/destruction
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dac76_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
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// When streaming is enabled, the Iref will be obtained from the input sound
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// stream. Otherwise, the value set with `set_fixed_iref` will be used.
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void configure_streaming_iref(bool streaming_iref);
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// By default, the control current (Iref) is treated as normalized ([0, 1],
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// defaults to 1), and the sound output is normalized to [-1, 1].
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//
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// When in "voltage output" mode, Iref (fixed or streaming) should be the
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// current flowing into pin 11, and the output will be a voltage stream.
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// `r_pos` is the feedback resistor of the I2V, which is also connected to
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// IOD+ (pin 16).
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// `r_neg` is the resistor to ground connected to IOD- (pin 17).
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// Note that r_pos connects to the "-" input of the I2V op-amp, and r_neg to
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// the "+" input.
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void configure_voltage_output(float i2v_r_pos, float i2v_r_neg);
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// Reference current. Ignored when streaming Iref mode is enabled.
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void set_fixed_iref(float iref);
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// chord
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void b1_w(int state) { m_chord &= ~(1 << 2); m_chord |= (state << 2); }
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void b2_w(int state) { m_chord &= ~(1 << 1); m_chord |= (state << 1); }
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@ -67,9 +99,17 @@ private:
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sound_stream *m_stream;
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// configuration
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bool m_streaming_iref;
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bool m_voltage_output;
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float m_r_pos;
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float m_r_neg;
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// state
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uint8_t m_chord; // 3-bit
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uint8_t m_step; // 4-bit
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bool m_sb;
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float m_fixed_iref;
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};
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// device type definition
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@ -209,7 +209,6 @@ protected:
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private:
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static void write_dac(dac76_device& dac, u8 sample);
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static float get_dac_scaler(float iref);
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static s32 get_ls267_freq(const std::array<s32, 2>& freq_range_hz, float cv);
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static float get_snare_tom_pitch_cv(float v);
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@ -243,7 +242,6 @@ private:
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required_memory_region m_sidestick_samples; // 2732 ROMs (U78).
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required_device<timer_device> m_snare_timer; // 74L627 (U80A).
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required_device<dac76_device> m_snare_dac; // AM6070 (U92).
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required_device<filter_volume_device> m_snare_volume; // R69, R72, R71, R70.
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required_device<filter_volume_device> m_snare_out; // U90A (CD4053) pin 12 (ax).
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required_device<filter_volume_device> m_sidestick_out; // U90A (CD4053) pin 13 (ay).
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required_device<timer_device> m_click_timer; // 556 (U65A).
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@ -305,6 +303,9 @@ private:
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static constexpr const float VCC = 5; // Volts.
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static constexpr const float MUX_DAC_IREF = VPLUS / (RES_K(15) + RES_K(15)); // R55 + R57.
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static constexpr const float TOM_DAC_IREF = MUX_DAC_IREF; // Configured in the same way.
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// All DAC current-to-voltage converter resistors, for both positive and
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// negative values, are 2.49 KOhm.
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static constexpr const float R_DAC_I2V = RES_K(2.49); // R58, R59, R127, R126, tom DAC I2V (missing designation).
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// Constants for hi hat envelope generator circuit.
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static constexpr const float HAT_C22 = CAP_U(1);
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@ -361,7 +362,6 @@ linndrum_audio_device::linndrum_audio_device(const machine_config &mconfig, cons
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, m_sidestick_samples(*this, ":sample_sidestick")
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, m_snare_timer(*this, "snare_sidestick_timer")
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, m_snare_dac(*this, "snare_sidestick_dac")
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, m_snare_volume(*this, "snare_sidestick_volume")
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, m_snare_out(*this, "snare_output")
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, m_sidestick_out(*this, "sidestick_output")
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, m_click_timer(*this, "click_timer")
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@ -465,12 +465,9 @@ void linndrum_audio_device::snare_w(u8 data)
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const float v2 = BIT(data, 2) ? VCC : 0;
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const float v3 = BIT(data, 3) ? VCC : 0;
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const float iref = (a * VPLUS + b * v2 + c * v3) / (R0 * (a + b + c + d));
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m_snare_dac->set_fixed_iref(iref);
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const float gain = get_dac_scaler(iref);
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m_snare_volume->set_gain(gain);
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LOGMASKED(LOG_STROBES, "Strobed snare / sidestick: %02x (iref: %f, gain: %f)\n",
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data, iref, gain);
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LOGMASKED(LOG_STROBES, "Strobed snare / sidestick: %02x (iref: %f)\n", data, iref);
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}
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void linndrum_audio_device::tom_w(u8 data)
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@ -572,8 +569,10 @@ void linndrum_audio_device::device_add_mconfig(machine_config &config)
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for (int voice = 0; voice < NUM_MUX_VOICES; ++voice)
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{
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DAC76(config, m_mux_dac[voice], 0); // AM6070 (U88).
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m_mux_dac[voice]->configure_voltage_output(R_DAC_I2V, R_DAC_I2V); // R58, R59.
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m_mux_dac[voice]->set_fixed_iref(MUX_DAC_IREF);
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FILTER_VOLUME(config, m_mux_volume[voice]); // CD4053 (U90), R60, R62 (see mux_drum_w()).
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m_mux_dac[voice]->add_route(0, m_mux_volume[voice], get_dac_scaler(MUX_DAC_IREF));
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m_mux_dac[voice]->add_route(0, m_mux_volume[voice], 1.0);
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}
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TIMER(config, m_hat_trigger_timer).configure_generic(FUNC(linndrum_audio_device::hat_trigger_timer_tick)); // LM556 (U37B).
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@ -586,17 +585,15 @@ void linndrum_audio_device::device_add_mconfig(machine_config &config)
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TIMER(config, m_snare_timer).configure_generic(FUNC(linndrum_audio_device::snare_timer_tick)); // 74LS627 (U80A).
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DAC76(config, m_snare_dac, 0); // AM6070 (U92)
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FILTER_VOLUME(config, m_snare_volume); // See snare_w().
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// DAC output scaling is incorporated in m_snare_volume's gain.
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m_snare_dac->add_route(0, m_snare_volume, 1.0);
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m_snare_dac->configure_voltage_output(R_DAC_I2V, R_DAC_I2V); // R127, R126.
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// The DAC's current outputs are processed by a current-to-voltage converter
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// that embeds an RC filter. This consists of an op-amp (U103), R127 and C65
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// (for positive voltages), and R126 and C31 (for negative voltages). The
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// two resistors and capacitors have the same value.
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auto &snare_dac_filter = FILTER_RC(config, "snare_sidestick_dac_filter");
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snare_dac_filter.set_lowpass(RES_K(2.49), CAP_P(2700)); // R127-C65, R126-C31. Cutoff: ~23.7KHz.
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m_snare_volume->add_route(0, snare_dac_filter, 1.0);
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snare_dac_filter.set_lowpass(R_DAC_I2V, CAP_P(2700)); // R127-C65, R126-C31. Cutoff: ~23.7KHz.
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m_snare_dac->add_route(0, snare_dac_filter, 1.0);
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FILTER_VOLUME(config, m_snare_out);
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FILTER_VOLUME(config, m_sidestick_out);
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@ -612,10 +609,14 @@ void linndrum_audio_device::device_add_mconfig(machine_config &config)
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TIMER(config, m_tom_timer).configure_generic(FUNC(linndrum_audio_device::tom_timer_tick)); // 74LS627 (U77B).
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DAC76(config, m_tom_dac, 0); // AM6070 (U82).
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// Schematic is missing the second resistor, but that's almost certainly an error.
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// It is also missing component designations.
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m_tom_dac->configure_voltage_output(R_DAC_I2V, R_DAC_I2V);
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m_tom_dac->set_fixed_iref(TOM_DAC_IREF);
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for (int i = 0; i < NUM_TOM_VOICES; ++i)
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{
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FILTER_VOLUME(config, m_tom_out[i]); // One of U87'S (CD4051) outputs.
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m_tom_dac->add_route(0, m_tom_out[i], get_dac_scaler(TOM_DAC_IREF));
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m_tom_dac->add_route(0, m_tom_out[i], 1.0);
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}
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// *** Mixer.
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@ -711,20 +712,6 @@ void linndrum_audio_device::write_dac(dac76_device &dac, u8 sample)
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dac.b7_w(BIT(sample, 0));
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}
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float linndrum_audio_device::get_dac_scaler(float iref)
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{
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// Given the reference current into the DAC, computes the scaler that needs
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// to be applied to the dac76_device output, to convert it to a voltage.
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// The maximum output current on each of the "+" and "-" outputs of the
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// AM6070 is `3.8 * Iref`, according to the datasheet.
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// That current gets converted to a voltage by an op-amp configured as
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// a current-to-voltage converter (I2V). All I2Vs on the LinnDrum use
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// 2.49K resistors for both the "+" and "-" current outputs of the DAC.
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return 3.8F * iref * float(RES_K(2.49));
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}
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s32 linndrum_audio_device::get_ls267_freq(const std::array<s32, 2>& freq_range, float cv)
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{
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// The relationship between CV and frequency is approximately linear. The
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@ -83,7 +83,6 @@ Usage notes:
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#include "sound/mixer.h"
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#include "sound/spkrdev.h"
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#include "sound/va_eg.h"
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#include "sound/va_vca.h"
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#include "video/dl1416.h"
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#include "speaker.h"
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@ -207,7 +206,6 @@ private:
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required_device<timer_device> m_timer; // 555, U5.
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required_device<dac76_device> m_dac; // AM6070, U8. Compatible with DAC76.
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required_device<va_vca_device> m_dac_mult; // AM6070 is a multiplying DAC.
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optional_device<va_rc_eg_device> m_eg; // Volume envelope generator. Input to U8 Iref.
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required_device_array<filter_biquad_device, 3> m_filters;
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@ -234,7 +232,6 @@ dmx_voice_card_device::dmx_voice_card_device(const machine_config &mconfig, cons
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, device_sound_interface(mconfig, *this)
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, m_timer(*this, "555_u5")
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, m_dac(*this, "dac_u8")
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, m_dac_mult(*this, "dac_mult_u8")
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, m_eg(*this, "envelope_generator")
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, m_filters(*this, "aa_sk_filter_%d", 0)
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, m_config(config)
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@ -249,7 +246,6 @@ dmx_voice_card_device::dmx_voice_card_device(const machine_config &mconfig, cons
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, device_sound_interface(mconfig, *this)
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, m_timer(*this, "555_u5")
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, m_dac(*this, "dac_u8")
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, m_dac_mult(*this, "dac_mult_u8")
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, m_eg(*this, "envelope_generator")
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, m_filters(*this, "aa_sk_filter_%d", 0)
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// Need non-zero entries for the filter for validation to pass.
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@ -281,7 +277,7 @@ void dmx_voice_card_device::trigger(bool tr0, bool tr1)
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if (has_decay()) // Gain is controled by an envelope generator.
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m_eg->set_instant_v(iref);
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else // Constant gain.
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m_dac_mult->set_fixed_cv(iref);
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m_dac->set_fixed_iref(iref);
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LOGMASKED(LOG_SOUND, "Trigger: (%d, %d) %d, %f uA\n", tr0, tr1, m_trigger_mode, iref * 1e6F);
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}
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@ -295,23 +291,17 @@ void dmx_voice_card_device::set_pitch_adj(s32 t1_percent)
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void dmx_voice_card_device::device_add_mconfig(machine_config &config)
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{
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// This multiplier relates the DAC reference current to the output voltage.
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// Iout = dac value (normalized to -1 - 1) * 3.8 * Iref.
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// Vout = Iout * R_current_to_voltage_converter.
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static constexpr const double DAC_MULTIPLIER = 3.8 * RES_K(2.4); // R16, R11 on voice card.
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static constexpr const double SK_R3 = RES_M(999.99);
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static constexpr const double SK_R4 = RES_R(0.001);
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TIMER(config, m_timer).configure_generic(FUNC(dmx_voice_card_device::clock_callback));
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DAC76(config, m_dac, 0U);
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VA_VCA(config, m_dac_mult);
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m_dac->add_route(0, m_dac_mult, DAC_MULTIPLIER);
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DAC76(config, m_dac, 0U).configure_voltage_output(RES_K(2.4), RES_K(2.4)); // R16, R11 on voice card.
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if (has_decay())
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{
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VA_RC_EG(config, m_eg).set_c(m_config.c3);
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m_dac_mult->configure_streaming_cv(true);
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m_eg->add_route(0, m_dac_mult, 1.0);
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m_dac->configure_streaming_iref(true);
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m_eg->add_route(0, m_dac, 1.0);
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}
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FILTER_BIQUAD(config, m_filters[0]).opamp_sk_lowpass_setup(
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@ -324,7 +314,7 @@ void dmx_voice_card_device::device_add_mconfig(machine_config &config)
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m_config.filter.r19, m_config.filter.r20, SK_R3, SK_R4,
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m_config.filter.c8, m_config.filter.c9);
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m_dac_mult->add_route(0, m_filters[0], 1.0);
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m_dac->add_route(0, m_filters[0], 1.0);
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m_filters[0]->add_route(0, m_filters[1], 1.0);
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m_filters[1]->add_route(0, m_filters[2], 1.0);
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m_filters[2]->add_route(0, *this, 1.0);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user