WIP: bit-banging I2C support for EEPROM access on QMOD
for now, it just continuously reads the EEPROM bytes and dumps them to
the serial console for testing.
diff --git a/firmware/src_simtrace/i2c.c b/firmware/src_simtrace/i2c.c
new file mode 100644
index 0000000..3a36888
--- /dev/null
+++ b/firmware/src_simtrace/i2c.c
@@ -0,0 +1,206 @@
+#include "board.h"
+#include <stdbool.h>
+
+/* Low-Level I2C Routines */
+
+static const Pin pin_sda = {PIO_PA30, PIOA, ID_PIOA, PIO_OUTPUT_1, PIO_OPENDRAIN };
+static const Pin pin_sda_in = {PIO_PA30, PIOA, ID_PIOA, PIO_INPUT, PIO_DEFAULT };
+static const Pin pin_scl = {PIO_PA31, PIOA, ID_PIOA, PIO_OUTPUT_1, PIO_OPENDRAIN };
+
+void i2c_pin_init(void)
+{
+ PIO_Configure(&pin_scl, PIO_LISTSIZE(pin_scl));
+ PIO_Configure(&pin_sda, PIO_LISTSIZE(pin_sda));
+}
+
+static void set_scl(void)
+{
+ PIO_Set(&pin_scl);
+}
+
+static void set_sda(void)
+{
+ PIO_Set(&pin_sda);
+}
+
+static void clear_scl(void)
+{
+ PIO_Clear(&pin_scl);
+}
+
+static void clear_sda(void)
+{
+ PIO_Clear(&pin_sda);
+}
+
+static bool read_sda(void)
+{
+ bool ret;
+
+ PIO_Configure(&pin_sda_in, PIO_LISTSIZE(pin_sda_in));
+ if (PIO_Get(&pin_sda))
+ ret = true;
+ else
+ ret = false;
+ PIO_Configure(&pin_sda, PIO_LISTSIZE(pin_sda));
+
+ return ret;
+}
+
+/* Core I2C Routines */
+
+static bool i2c_started = false;
+
+static void i2c_delay()
+{
+ volatile int v;
+ int i;
+
+ for (i = 0; i < 100; i++) {
+ v = 0;
+ }
+}
+
+static void i2c_start_cond(void)
+{
+ if (i2c_started) {
+ set_sda();
+ i2c_delay();
+ set_scl();
+ i2c_delay();
+ }
+
+ i2c_delay();
+ clear_sda();
+ i2c_delay();
+ clear_scl();
+ i2c_started = true;
+}
+
+static void i2c_stop_cond(void)
+{
+ clear_sda();
+ i2c_delay();
+ set_scl();
+ i2c_delay();
+ set_sda();
+ i2c_delay();
+ i2c_started = false;
+}
+
+static void i2c_write_bit(bool bit)
+{
+ if (bit)
+ set_sda();
+ else
+ clear_sda();
+ i2c_delay();
+ set_scl();
+ i2c_delay();
+ clear_scl();
+ i2c_delay();
+}
+
+static bool i2c_read_bit(void)
+{
+ bool bit;
+
+ set_sda();
+ i2c_delay();
+ set_scl();
+ i2c_delay();
+ bit = read_sda();
+ clear_scl();
+
+ return bit;
+}
+
+bool i2c_write_byte(bool send_start, bool send_stop, uint8_t byte)
+{
+ uint8_t bit;
+ bool nack;
+
+ if (send_start)
+ i2c_start_cond();
+
+ for (bit = 0; bit < 8; bit++) {
+ i2c_write_bit((byte & 0x80) != 0);
+ byte <<= 1;
+ }
+
+ nack = i2c_read_bit();
+
+ if (send_stop)
+ i2c_stop_cond();
+
+ return nack;
+}
+
+uint8_t i2c_read_byte(bool nack, bool send_stop)
+{
+ uint8_t byte = 0;
+ uint8_t bit;
+
+ for (bit = 0; bit < 8; bit++) {
+ byte = (byte << 1) | i2c_read_bit();
+ }
+
+ i2c_write_bit(nack);
+
+ if (send_stop)
+ i2c_stop_cond();
+
+ return byte;
+}
+
+
+/* EEPROM related code */
+
+int eeprom_write_byte(uint8_t slave, uint8_t addr, uint8_t byte)
+{
+ bool nack;
+
+ /* Write slave address */
+ nack = i2c_write_byte(true, false, slave << 1);
+ if (nack)
+ goto out_stop;
+ nack = i2c_write_byte(false, false, addr);
+ if (nack)
+ goto out_stop;
+ nack = i2c_write_byte(false, true, byte);
+ if (nack)
+ goto out_stop;
+
+out_stop:
+ i2c_stop_cond();
+ if (nack)
+ return -1;
+ else
+ return 0;
+}
+
+int eeprom_read_byte(uint8_t slave, uint8_t addr)
+{
+ bool nack;
+
+ /* dummy write cycle */
+ nack = i2c_write_byte(true, false, slave << 1);
+ if (nack)
+ goto out_stop;
+ nack = i2c_write_byte(false, false, addr);
+ if (nack)
+ goto out_stop;
+ /* Re-start with read */
+ nack = i2c_write_byte(true, false, (slave << 1) | 1);
+ if (nack)
+ goto out_stop;
+
+ return i2c_read_byte(true, true);
+
+out_stop:
+ i2c_stop_cond();
+ if (nack)
+ return -1;
+ else
+ return 0;
+}
diff --git a/firmware/src_simtrace/i2c.h b/firmware/src_simtrace/i2c.h
new file mode 100644
index 0000000..15e4b37
--- /dev/null
+++ b/firmware/src_simtrace/i2c.h
@@ -0,0 +1,5 @@
+#pragma once
+
+void i2c_pin_init(void);
+int eeprom_write_byte(uint8_t slave, uint8_t addr, uint8_t byte);
+int eeprom_read_byte(uint8_t slave, uint8_t addr);
diff --git a/firmware/src_simtrace/main.c b/firmware/src_simtrace/main.c
index 5d5e332..c4e6f3c 100644
--- a/firmware/src_simtrace/main.c
+++ b/firmware/src_simtrace/main.c
@@ -97,6 +97,7 @@
config_func_ptrs[simtrace_config].usart0_irq();
}
+#include "i2c.h"
/*------------------------------------------------------------------------------
* Main
*------------------------------------------------------------------------------*/
@@ -131,6 +132,18 @@
g_unique_id[0], g_unique_id[1],
g_unique_id[2], g_unique_id[3]);
+#if 1
+ static const Pin pin_hub_rst = {PIO_PA13, PIOA, ID_PIOA, PIO_OUTPUT_1, PIO_DEFAULT};
+ PIO_Configure(&pin_hub_rst, 1);
+ i2c_pin_init();
+ while (1) {
+ for (i = 0; i < 256; i ++) {
+ int byte = eeprom_read_byte(0x50, i);
+ TRACE_INFO("0x%02x: %02x\r\n", i, byte);
+ }
+ }
+#endif
+
TRACE_INFO("USB init...\r\n");
while (USBD_GetState() < USBD_STATE_CONFIGURED) {
if (i >= MAX_USB_ITER * 3) {