spi_sdcard: Added CMD1 SEND_OP_COND.

- Fixed CMD10 R1 response, not idle.
- Delay SPI response by 1 byte, required for MMFS.
- Only latch data on clock edges.

src/devices/machine/spi_sdcard.cpp

@@ -16,9 +16,9 @@
 
     Multiple block read/write commands are not supported but would be straightforward to add.
 
-    Refrences:
+    References:
     https://www.sdcard.org/downloads/pls/ (Physical Layer Simplified Specification)
-    REF: tags are refering to the spec form above. 'Physical Layer Simplified Specification v8.00'
+    REF: tags are referring to the spec form above. 'Physical Layer Simplified Specification v8.00'
 
     http://www.dejazzer.com/ee379/lecture_notes/lec12_sd_card.pdf
     https://embdev.net/attachment/39390/TOSHIBA_SD_Card_Specification.pdf
@@ -50,7 +50,7 @@ spi_sdcard_device::spi_sdcard_device(const machine_config &mconfig, device_type
 	m_image(*this, "image"),
 	m_state(SD_STATE_IDLE),
 	m_harddisk(nullptr),
-	m_ss(0), m_in_bit(0),
+	m_ss(0), m_in_bit(0), m_clk_state(0),
 	m_in_latch(0), m_out_latch(0xff), m_cur_bit(0),
 	m_out_count(0), m_out_ptr(0), m_write_ptr(0), m_blksize(512), m_blknext(0),
 	m_bACMD(false)
@@ -82,6 +82,7 @@ void spi_sdcard_device::device_start()
 	save_item(NAME(m_out_count));
 	save_item(NAME(m_ss));
 	save_item(NAME(m_in_bit));
+	save_item(NAME(m_clk_state));
 	save_item(NAME(m_cur_bit));
 	save_item(NAME(m_write_ptr));
 	save_item(NAME(m_blksize));
@@ -111,17 +112,24 @@ void spi_sdcard_device::send_data(u16 count, sd_state new_state)
 
 void spi_sdcard_device::spi_clock_w(int state)
 {
-	// only respond if selected
+	// only respond if selected, and a clock edge
-	if (m_ss)
+	if (m_ss && state != m_clk_state)
 	{
-		// We implmement SPI Mode 3 signalling, in which we latch the data on
+		// We implement SPI Mode 3 signalling, in which we latch the data on
 		// rising clock edges, and shift the data on falling clock edges.
 		// See http://www.dejazzer.com/ee379/lecture_notes/lec12_sd_card.pdf for details
-		// on the 4 SPI signalling modes.  SD Cards can work in ether Mode 0 or Mode 3,
+		// on the 4 SPI signalling modes. SD Cards can work in either Mode 0 or Mode 3,
 		// both of which shift on the falling edge and latch on the rising edge but
 		// have opposite CLK polarity.
-
 		if (state)
+			latch_in();
+		else
+			shift_out();
+	}
+	m_clk_state = state;
+}
+
+void spi_sdcard_device::latch_in()
 {
 	m_in_latch &= ~0x01;
 	m_in_latch |= m_in_bit;
@@ -200,28 +208,31 @@ void spi_sdcard_device::spi_clock_w(int state)
 		}
 	}
 }
-		else
+
+void spi_sdcard_device::shift_out()
 {
 	m_in_latch <<= 1;
 	m_out_latch <<= 1;
 	m_out_latch |= 1;
-			LOGMASKED(LOG_SPI, "\tsdcard: S %02x %02x (%d)\n", m_in_latch,
+	LOGMASKED(LOG_SPI, "\tsdcard: S %02x %02x (%d)\n", m_in_latch, m_out_latch, m_cur_bit);
-					  m_out_latch, m_cur_bit);
 
 	m_cur_bit &= 0x07;
 	if (m_cur_bit == 0)
 	{
-				if (m_out_count > 0)
+		if (m_out_ptr < SPI_DELAY_RESPONSE)
 		{
-					m_out_latch = m_data[m_out_ptr++];
+			m_out_ptr++;
+		}
+		else if (m_out_count > 0)
+		{
+			m_out_latch = m_data[m_out_ptr - SPI_DELAY_RESPONSE];
+			m_out_ptr++;
 			LOGMASKED(LOG_SPI, "SDCARD: latching %02x (start of shift)\n", m_out_latch);
 			m_out_count--;
 		}
 	}
 	write_miso(BIT(m_out_latch, 7));
 }
-	}
-}
 
 void spi_sdcard_device::do_command()
 {
@@ -244,6 +255,11 @@ void spi_sdcard_device::do_command()
 			}
 			break;
 
+		case 1: // CMD1 - SEND_OP_COND
+			m_data[0] = 0x00;
+			send_data(1, SD_STATE_READY);
+			break;
+
 		case 8: // CMD8 - SEND_IF_COND (SD v2 only)
 			m_data[0] = 0x01;
 			m_data[1] = 0;
@@ -254,8 +270,8 @@ void spi_sdcard_device::do_command()
 			break;
 
 		case 10: // CMD10 - SEND_CID
-			m_data[0] = 0x01; // initial R1 response
+			m_data[0] = 0x00; // initial R1 response
-			m_data[1] = 0x00; // throwaway byte before data transfer
+			m_data[1] = 0xff; // throwaway byte before data transfer
 			m_data[2] = 0xfe; // data token
 			m_data[3] = 'M';  // Manufacturer ID - we'll use M for MAME
 			m_data[4] = 'M';  // OEM ID - MD for MAMEdev
@@ -286,13 +302,12 @@ void spi_sdcard_device::do_command()
 
 		case 12: // CMD12 - STOP_TRANSMISSION
 			m_data[0] = 0;
-			send_data(1,
+			send_data(1, m_state == SD_STATE_RCV ? SD_STATE_PRG : SD_STATE_TRAN);
-					  m_state == SD_STATE_RCV ? SD_STATE_PRG : SD_STATE_TRAN);
 			break;
 
 		case 16: // CMD16 - SET_BLOCKLEN
 			m_blksize = (u16(m_cmd[3]) << 8) | u16(m_cmd[4]);
-			if (m_harddisk->set_block_size(m_blksize))
+			if (m_harddisk && m_harddisk->set_block_size(m_blksize))
 			{
 				m_data[0] = 0;
 			}
@@ -301,9 +316,7 @@ void spi_sdcard_device::do_command()
 				m_data[0] = 0xff; // indicate an error
 				// if false was returned, it means the hard disk is a CHD file, and we can't resize the
 				// blocks on CHD files.
-				logerror("spi_sdcard: Couldn't change block size to %d, wrong "
+				logerror("spi_sdcard: Couldn't change block size to %d, wrong CHD file?", m_blksize);
-						 "CHD file?",
-						 m_blksize);
 			}
 			send_data(1, SD_STATE_TRAN);
 			break;

src/devices/machine/spi_sdcard.h

@@ -53,20 +53,26 @@ private:
 		SD_STATE_DIS,
 		SD_STATE_INA,
 
-		//FIXME Existing states wich must be revisited
+		//FIXME Existing states which must be revisited
 		SD_STATE_WRITE_WAITFE,
 		SD_STATE_WRITE_DATA
 	};
 	sd_state m_state;
 
+	// MMFS for Acorn machines expect dummy byte before response
+	static constexpr int SPI_DELAY_RESPONSE = 1;
+
 	void send_data(u16 count, sd_state new_state);
 	void do_command();
 	void change_state(sd_state new_state);
 
+	void latch_in();
+	void shift_out();
+
 	u8 m_data[520], m_cmd[6];
 	hard_disk_file *m_harddisk;
 
-	int m_ss, m_in_bit;
+	int m_ss, m_in_bit, m_clk_state;
 	u8 m_in_latch, m_out_latch, m_cur_bit;
 	u16 m_out_count, m_out_ptr, m_write_ptr, m_blksize;
 	u32 m_blknext;