hd44780: Add alternate interface using direct writes to bus control lines (nw)

This is necessitated by an odd edge case where the LCD controller is addressed in 4-bit mode and the busy flag is polled continuously by setting R/W = 1, RS = 0 and E = 0 and then just waiting for DB7 to be cleared. In this case, the ordinary read operation will select an alternate nibble each time, resulting in spurious values.

Hitachi's HD44780 datasheet does not actually recommend this polling method, so it might actually be for one of the many compatible LCD controllers from other manufacturers.
This commit is contained in:
AJR 2019-08-25 11:20:52 -04:00
parent 45ffa4d01d
commit 873d65e11e
13 changed files with 138 additions and 85 deletions

View File

@ -57,6 +57,10 @@ hd44780_device::hd44780_device(const machine_config &mconfig, device_type type,
: device_t(mconfig, type, tag, owner, clock)
, m_cgrom(nullptr)
, m_cgrom_region(*this, DEVICE_SELF)
, m_rs_input(0)
, m_rw_input(0)
, m_db_input(0)
, m_enabled(false)
{
}
@ -115,6 +119,10 @@ void hd44780_device::device_start()
save_item(NAME(m_ddram));
save_item(NAME(m_cgram));
save_item(NAME(m_nibble));
save_item(NAME(m_rs_input));
save_item(NAME(m_rw_input));
save_item(NAME(m_db_input));
save_item(NAME(m_enabled));
save_item(NAME(m_rs_state));
save_item(NAME(m_rw_state));
}
@ -234,7 +242,7 @@ void hd44780_device::update_nibble(int rs, int rw)
m_nibble = !m_nibble;
}
inline void hd44780_device::pixel_update(bitmap_ind16 &bitmap, uint8_t line, uint8_t pos, uint8_t y, uint8_t x, int state)
inline void hd44780_device::pixel_update(bitmap_ind16 &bitmap, u8 line, u8 pos, u8 y, u8 x, int state)
{
if (!m_pixel_update_cb.isnull())
{
@ -242,7 +250,7 @@ inline void hd44780_device::pixel_update(bitmap_ind16 &bitmap, uint8_t line, uin
}
else
{
uint8_t line_height = (m_char_size == 8) ? m_char_size : m_char_size + 1;
u8 line_height = (m_char_size == 8) ? m_char_size : m_char_size + 1;
if (m_lines <= 2)
{
@ -275,13 +283,13 @@ inline void hd44780_device::pixel_update(bitmap_ind16 &bitmap, uint8_t line, uin
// device interface
//**************************************************************************
const uint8_t *hd44780_device::render()
const u8 *hd44780_device::render()
{
memset(m_render_buf, 0, sizeof(m_render_buf));
if (m_display_on)
{
uint8_t line_size = 80 / m_num_line;
u8 line_size = 80 / m_num_line;
for (int line = 0; line < m_num_line; line++)
{
@ -304,8 +312,8 @@ const uint8_t *hd44780_device::render()
char_base = m_ddram[char_pos] * 0x10;
}
const uint8_t * charset = (m_ddram[char_pos] < 0x10) ? m_cgram : m_cgrom;
uint8_t *dest = m_render_buf + 16 * (line * line_size + pos);
const u8 *charset = (m_ddram[char_pos] < 0x10) ? m_cgram : m_cgrom;
u8 *dest = m_render_buf + 16 * (line * line_size + pos);
memcpy (dest, charset + char_base, m_char_size);
if (char_pos == m_ac)
@ -327,15 +335,15 @@ const uint8_t *hd44780_device::render()
uint32_t hd44780_device::screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
bitmap.fill(0, cliprect);
const uint8_t *img = render();
const u8 *img = render();
uint8_t line_size = 80 / m_num_line;
u8 line_size = 80 / m_num_line;
for (int line = 0; line < m_num_line; line++)
{
for (int pos = 0; pos < line_size; pos++)
{
const uint8_t *src = img + 16 * (line * line_size + pos);
const u8 *src = img + 16 * (line * line_size + pos);
for (int y = 0; y < m_char_size; y++)
for (int x = 0; x < 5; x++)
pixel_update(bitmap, line, pos, y, x, BIT(src[y], 4 - x));
@ -347,6 +355,9 @@ uint32_t hd44780_device::screen_update(screen_device &screen, bitmap_ind16 &bitm
u8 hd44780_device::read(offs_t offset)
{
if (m_data_len == 4 && !machine().side_effects_disabled())
update_nibble(offset & 0x01, 1);
switch (offset & 0x01)
{
case 0: return control_read();
@ -358,6 +369,9 @@ u8 hd44780_device::read(offs_t offset)
void hd44780_device::write(offs_t offset, u8 data)
{
if (m_data_len == 4 && !machine().side_effects_disabled())
update_nibble(offset & 0x01, 0);
switch (offset & 0x01)
{
case 0: control_write(data); break;
@ -365,12 +379,56 @@ void hd44780_device::write(offs_t offset, u8 data)
}
}
u8 hd44780_device::db_r()
{
if (m_enabled && m_rw_input == 1)
{
switch (m_rs_input)
{
case 0: return control_read();
case 1: return data_read();
}
}
return 0xff;
}
void hd44780_device::db_w(u8 data)
{
m_db_input = data;
}
WRITE_LINE_MEMBER(hd44780_device::rs_w)
{
m_rs_input = state;
}
WRITE_LINE_MEMBER(hd44780_device::rw_w)
{
m_rw_input = state;
}
WRITE_LINE_MEMBER(hd44780_device::e_w)
{
if (m_data_len == 4 && state && !m_enabled && !machine().side_effects_disabled())
update_nibble(m_rs_input, m_rw_input);
if (!state && m_enabled && m_rw_input == 0)
{
switch (m_rs_input)
{
case 0: control_write(m_db_input); break;
case 1: data_write(m_db_input); break;
}
}
m_enabled = state;
}
void hd44780_device::control_write(u8 data)
{
if (m_data_len == 4)
{
update_nibble(0, 0);
if (m_nibble)
{
m_ir = data & 0xf0;
@ -489,9 +547,6 @@ u8 hd44780_device::control_read()
{
if (m_data_len == 4)
{
if (!machine().side_effects_disabled())
update_nibble(0, 1);
if (m_nibble)
return (m_busy_flag ? 0x80 : 0) | (m_ac & 0x70);
else
@ -513,8 +568,6 @@ void hd44780_device::data_write(u8 data)
if (m_data_len == 4)
{
update_nibble(1, 0);
if (m_nibble)
{
m_dr = data & 0xf0;
@ -545,15 +598,12 @@ void hd44780_device::data_write(u8 data)
u8 hd44780_device::data_read()
{
uint8_t data = (m_active_ram == DDRAM) ? m_ddram[m_ac] : m_cgram[m_ac];
u8 data = (m_active_ram == DDRAM) ? m_ddram[m_ac] : m_cgram[m_ac];
LOG("HD44780: %sRAM read %x %c\n", m_active_ram == DDRAM ? "DD" : "CG", m_ac, data);
if (m_data_len == 4)
{
if (!machine().side_effects_disabled())
update_nibble(1, 1);
if (m_nibble)
return data & 0xf0;
else

View File

@ -16,7 +16,7 @@
// TYPE DEFINITIONS
//**************************************************************************
#define HD44780_PIXEL_UPDATE(name) void name(bitmap_ind16 &bitmap, uint8_t line, uint8_t pos, uint8_t y, uint8_t x, int state)
#define HD44780_PIXEL_UPDATE(name) void name(bitmap_ind16 &bitmap, u8 line, u8 pos, u8 y, u8 x, int state)
// ======================> hd44780_device
@ -24,7 +24,7 @@
class hd44780_device : public device_t
{
public:
typedef device_delegate<void (bitmap_ind16 &bitmap, uint8_t line, uint8_t pos, uint8_t y, uint8_t x, int state)> pixel_update_delegate;
typedef device_delegate<void (bitmap_ind16 &bitmap, u8 line, u8 pos, u8 y, u8 x, int state)> pixel_update_delegate;
// construction/destruction
hd44780_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock = 0);
@ -34,25 +34,31 @@ public:
template <typename... T> void set_pixel_update_cb(T &&... args) { m_pixel_update_cb = pixel_update_delegate(std::forward<T>(args)...); }
void set_pixel_update_cb(pixel_update_delegate callback) { m_pixel_update_cb = callback; }
template <class FunctionClass> void set_pixel_update_cb(const char *devname,
void (FunctionClass::*callback)(bitmap_ind16 &, uint8_t, uint8_t, uint8_t, uint8_t, int), const char *name)
void (FunctionClass::*callback)(bitmap_ind16 &, u8, u8, u8, u8, int), const char *name)
{
set_pixel_update_cb(pixel_update_delegate(callback, name, devname, static_cast<FunctionClass *>(nullptr)));
}
template <class FunctionClass> void set_pixel_update_cb(
void (FunctionClass::*callback)(bitmap_ind16 &, uint8_t, uint8_t, uint8_t, uint8_t, int), const char *name)
void (FunctionClass::*callback)(bitmap_ind16 &, u8, u8, u8, u8, int), const char *name)
{
set_pixel_update_cb(pixel_update_delegate(callback, name, nullptr, static_cast<FunctionClass *>(nullptr)));
}
// device interface
virtual void write(offs_t offset, u8 data);
virtual u8 read(offs_t offset);
virtual void control_write(u8 data);
virtual u8 control_read();
virtual void data_write(u8 data);
virtual u8 data_read();
void write(offs_t offset, u8 data);
u8 read(offs_t offset);
void control_w(u8 data) { write(0, data); }
u8 control_r() { return read(0); }
void data_w(u8 data) { write(1, data); }
u8 data_r() { return read(1); }
const uint8_t *render();
u8 db_r();
void db_w(u8 data);
DECLARE_WRITE_LINE_MEMBER(rs_w);
DECLARE_WRITE_LINE_MEMBER(rw_w);
DECLARE_WRITE_LINE_MEMBER(e_w);
const u8 *render();
virtual uint32_t screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);
protected:
@ -81,6 +87,11 @@ protected:
*/
};
virtual void control_write(u8 data);
virtual u8 control_read();
virtual void data_write(u8 data);
virtual u8 data_read();
void set_charset_type(int type);
private:
@ -90,7 +101,7 @@ private:
void update_ac(int direction);
void update_nibble(int rs, int rw);
void shift_display(int direction);
void pixel_update(bitmap_ind16 &bitmap, uint8_t line, uint8_t pos, uint8_t y, uint8_t x, int state);
void pixel_update(bitmap_ind16 &bitmap, u8 line, u8 pos, u8 y, u8 x, int state);
// internal state
static constexpr device_timer_id TIMER_BUSY = 0;
@ -99,35 +110,39 @@ private:
emu_timer * m_blink_timer;
emu_timer * m_busy_timer;
uint8_t m_lines; // number of lines
uint8_t m_chars; // chars for line
u8 m_lines; // number of lines
u8 m_chars; // chars for line
pixel_update_delegate m_pixel_update_cb; // pixel update callback
bool m_busy_flag; // busy flag
uint8_t m_ddram[0x80]; // internal display data RAM
uint8_t m_cgram[0x40]; // internal chargen RAM
uint8_t const *m_cgrom;
optional_region_ptr<uint8_t> m_cgrom_region; // internal chargen ROM
u8 m_ddram[0x80]; // internal display data RAM
u8 m_cgram[0x40]; // internal chargen RAM
u8 const *m_cgrom;
optional_region_ptr<u8> m_cgrom_region; // internal chargen ROM
int m_ac; // address counter
uint8_t m_dr; // data register
uint8_t m_ir; // instruction register
uint8_t m_active_ram; // DDRAM or CGRAM
u8 m_dr; // data register
u8 m_ir; // instruction register
u8 m_active_ram; // DDRAM or CGRAM
bool m_display_on; // display on/off
bool m_cursor_on; // cursor on/off
bool m_blink_on; // blink on/off
bool m_shift_on; // shift on/off
int m_disp_shift; // display shift
int m_direction; // auto increment/decrement (-1 or +1)
uint8_t m_data_len; // interface data length 4 or 8 bit
uint8_t m_num_line; // number of lines
uint8_t m_char_size; // char size 5x8 or 5x10
u8 m_data_len; // interface data length 4 or 8 bit
u8 m_num_line; // number of lines
u8 m_char_size; // char size 5x8 or 5x10
bool m_blink;
bool m_first_cmd;
int m_rs_input;
int m_rw_input;
u8 m_db_input;
bool m_enabled;
int m_rs_state;
int m_rw_state;
bool m_nibble;
int m_charset_type;
uint8_t m_render_buf[80 * 16];
u8 m_render_buf[80 * 16];
enum { DDRAM, CGRAM };
};

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@ -89,8 +89,7 @@ void fb01_state::fb01_io(address_map &map)
map(0x20, 0x20).portr("PANEL");
// 30-31 HD44780A
map(0x30, 0x30).rw("hd44780", FUNC(hd44780_device::control_read), FUNC(hd44780_device::control_write));
map(0x31, 0x31).rw("hd44780", FUNC(hd44780_device::data_read), FUNC(hd44780_device::data_write));
map(0x30, 0x31).rw("hd44780", FUNC(hd44780_device::read), FUNC(hd44780_device::write));
}

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@ -135,10 +135,10 @@ void hprot1_state::i80c31_io(address_map &map)
{
map(0x0000, 0x7fff).ram();
/*TODO: verify the mirror mask value for the HD44780 device */
map(0xc000, 0xc000).mirror(0x13cf).w(m_lcdc, FUNC(hd44780_device::control_write));
map(0xc010, 0xc010).mirror(0x13cf).w(m_lcdc, FUNC(hd44780_device::data_write));
map(0xc020, 0xc020).mirror(0x13cf).r(m_lcdc, FUNC(hd44780_device::control_read));
map(0xc030, 0xc030).mirror(0x13cf).r(m_lcdc, FUNC(hd44780_device::data_read));
map(0xc000, 0xc000).mirror(0x13cf).w(m_lcdc, FUNC(hd44780_device::control_w));
map(0xc010, 0xc010).mirror(0x13cf).w(m_lcdc, FUNC(hd44780_device::data_w));
map(0xc020, 0xc020).mirror(0x13cf).r(m_lcdc, FUNC(hd44780_device::control_r));
map(0xc030, 0xc030).mirror(0x13cf).r(m_lcdc, FUNC(hd44780_device::data_r));
/*TODO: attach the watchdog/brownout reset device:
map(0xe000,0xe0??).mirror(?).r("adm965an", FUNC(adm965an_device::data_read)); */
}

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@ -89,8 +89,7 @@ void icatel_state::i80c31_io(address_map &map)
{
map(0x0000, 0x3FFF).ram();
map(0x8000, 0x8002).ram(); /* HACK! */
map(0x8040, 0x8040).mirror(0x3F1E).w(m_lcdc, FUNC(hd44780_device::control_write)); // not sure yet. CI12 (73LS273)
map(0x8041, 0x8041).mirror(0x3F1E).w(m_lcdc, FUNC(hd44780_device::data_write)); // not sure yet. CI12
map(0x8040, 0x8041).mirror(0x3F1E).w(m_lcdc, FUNC(hd44780_device::write)); // not sure yet. CI12 (73LS273)
map(0x8060, 0x8060).mirror(0x3F1F).rw(FUNC(icatel_state::ci8_r), FUNC(icatel_state::ci8_w));
map(0x8080, 0x8080).mirror(0x3F1F).rw(FUNC(icatel_state::ci16_r), FUNC(icatel_state::ci16_w)); // card reader (?)
map(0x80C0, 0x80C0).mirror(0x3F1F).rw(FUNC(icatel_state::ci15_r), FUNC(icatel_state::ci15_w)); // 74LS244 (tristate buffer)

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@ -111,10 +111,8 @@ void lcmate2_state::lcmate2_io(address_map &map)
map(0x1000, 0x1000).w(FUNC(lcmate2_state::speaker_w));
map(0x1fff, 0x1fff).w(FUNC(lcmate2_state::bankswitch_w));
map(0x3000, 0x3000).w(m_lcdc, FUNC(hd44780_device::control_write));
map(0x3001, 0x3001).w(m_lcdc, FUNC(hd44780_device::data_write));
map(0x3002, 0x3002).r(m_lcdc, FUNC(hd44780_device::control_read));
map(0x3003, 0x3003).r(m_lcdc, FUNC(hd44780_device::data_read));
map(0x3000, 0x3001).w(m_lcdc, FUNC(hd44780_device::write));
map(0x3002, 0x3003).r(m_lcdc, FUNC(hd44780_device::read));
map(0x5000, 0x50ff).r(FUNC(lcmate2_state::key_r));
}

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@ -112,8 +112,8 @@ void ml20_state::mem_map(address_map &map)
void ml20_state::io_map(address_map &map)
{
map(0x00, 0x0f).rw("rtc", FUNC(msm6242_device::read), FUNC(msm6242_device::write));
map(0x10, 0x10).rw(m_lcdc, FUNC(hd44780_device::data_read), FUNC(hd44780_device::data_write));
map(0x14, 0x14).rw(m_lcdc, FUNC(hd44780_device::control_read), FUNC(hd44780_device::control_write));
map(0x10, 0x10).rw(m_lcdc, FUNC(hd44780_device::data_r), FUNC(hd44780_device::data_w));
map(0x14, 0x14).rw(m_lcdc, FUNC(hd44780_device::control_r), FUNC(hd44780_device::control_w));
}
static INPUT_PORTS_START( ml20 )

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@ -364,7 +364,7 @@ READ8_MEMBER( pc1000_state::kb_r )
READ8_MEMBER( pc1000_state::lcdc_data_r )
{
//logerror("lcdc data r\n");
return m_lcdc->data_read() >> 4;
return m_lcdc->data_r() >> 4;
}
WRITE8_MEMBER( pc1000_state::lcdc_data_w )
@ -372,19 +372,19 @@ WRITE8_MEMBER( pc1000_state::lcdc_data_w )
//popmessage("%s", (char*)m_maincpu->space(AS_PROGRAM).get_read_ptr(0x4290));
//logerror("lcdc data w %x\n", data);
m_lcdc->data_write(data << 4);
m_lcdc->data_w(data << 4);
}
READ8_MEMBER( pc1000_state::lcdc_control_r )
{
//logerror("lcdc control r\n");
return m_lcdc->control_read() >> 4;
return m_lcdc->control_r() >> 4;
}
WRITE8_MEMBER( pc1000_state::lcdc_control_w )
{
//logerror("lcdc control w %x\n", data);
m_lcdc->control_write(data<<4);
m_lcdc->control_w(data<<4);
}
HD44780_PIXEL_UPDATE(pc1000_state::pc1000_pixel_update)

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@ -95,13 +95,14 @@ WRITE8_MEMBER(piggypas_state::led_strobe_w)
READ8_MEMBER(piggypas_state::lcd_latch_r)
{
return m_lcd_latch;
return m_hd44780->db_r();
}
WRITE8_MEMBER(piggypas_state::lcd_latch_w)
{
// P1.7 might also be used to reset DS1232 watchdog
m_lcd_latch = data;
m_hd44780->db_w(data);
}
WRITE8_MEMBER(piggypas_state::lcd_control_w)
@ -109,13 +110,9 @@ WRITE8_MEMBER(piggypas_state::lcd_control_w)
// RXD (P3.0) = chip select
// TXD (P3.1) = register select
// INT0 (P3.2) = R/W
if (BIT(data, 0))
{
if (BIT(data, 2))
m_lcd_latch = m_hd44780->read(BIT(data, 1));
else
m_hd44780->write(BIT(data, 1), m_lcd_latch);
}
m_hd44780->e_w(BIT(data, 0));
m_hd44780->rs_w(BIT(data, 1));
m_hd44780->rw_w(BIT(data, 2));
// T0 (P3.4) = output shift clock (serial data present at P1.0)
// T1 (P3.5) = output latch enable

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@ -252,8 +252,7 @@ void psion1_state::psion1_mem(address_map &map)
{
map(0x0000, 0x001f).rw(FUNC(psion1_state::hd63701_int_reg_r), FUNC(psion1_state::hd63701_int_reg_w));
map(0x0040, 0x00ff).ram().share("sys_register");
map(0x2000, 0x2000).mirror(0x07fe).rw(m_lcdc, FUNC(hd44780_device::control_read), FUNC(hd44780_device::control_write));
map(0x2001, 0x2001).mirror(0x07fe).rw(m_lcdc, FUNC(hd44780_device::data_read), FUNC(hd44780_device::data_write));
map(0x2000, 0x2001).mirror(0x07fe).rw(m_lcdc, FUNC(hd44780_device::read), FUNC(hd44780_device::write));
map(0x2800, 0x2800).r(FUNC(psion1_state::reset_kb_counter_r));
map(0x2e00, 0x2e00).r(FUNC(psion1_state::switchoff_r));
map(0x3000, 0x3000).r(FUNC(psion1_state::inc_kb_counter_r));

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@ -360,11 +360,7 @@ WRITE8_MEMBER(replicator_state::port_w)
uint8_t lcd_data = shift_register_value & 0xF0;
if (enable && RW==0){
if (RS==0){
m_lcdc->control_write(lcd_data);
} else {
m_lcdc->data_write(lcd_data);
}
m_lcdc->write(RS, lcd_data);
}
}
}

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@ -83,9 +83,9 @@ void ti630_state::init_ti630()
void ti630_state::i80c31_io(address_map &map)
{
map(0x0000, 0x0000) /*.mirror(?)*/ .w("hd44780", FUNC(hd44780_device::control_write));
map(0x1000, 0x1000) /*.mirror(?)*/ .w("hd44780", FUNC(hd44780_device::data_write));
map(0x2000, 0x2000) /*.mirror(?)*/ .r("hd44780", FUNC(hd44780_device::control_read));
map(0x0000, 0x0000) /*.mirror(?)*/ .w("hd44780", FUNC(hd44780_device::control_w));
map(0x1000, 0x1000) /*.mirror(?)*/ .w("hd44780", FUNC(hd44780_device::data_w));
map(0x2000, 0x2000) /*.mirror(?)*/ .r("hd44780", FUNC(hd44780_device::control_r));
map(0x8000, 0xffff).ram(); /*TODO: verify the ammont of RAM and the correct address range to which it is mapped. This is just a first reasonable guess that apparently yields good results in the emulation */
}

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@ -19,10 +19,10 @@ public:
void set_contrast(float contrast) { m_contrast = contrast; }
void set_leds(u8 leds) { m_leds = leds; }
u8 data_read() { return m_lcd->data_read(); }
u8 control_read() { return m_lcd->control_read(); }
void data_write(u8 data) { m_lcd->data_write(data); }
void control_write(u8 data) { m_lcd->control_write(data); }
u8 data_read() { return m_lcd->data_r(); }
u8 control_read() { return m_lcd->control_r(); }
void data_write(u8 data) { m_lcd->data_w(data); }
void control_write(u8 data) { m_lcd->control_w(data); }
protected: