rfdsatt: add low-level EEPROM read/write support

projects/rfdsatt/Makefile

@@ -19,7 +19,7 @@
 
 BINARY = rfdsatt
 
-OBJS =	attenuator.o board_rfdsatt_4ch.o
+OBJS =	attenuator.o eeprom.o board_rfdsatt_4ch.o
 
 # when building for M0
 #LDSCRIPT = ./stm32f051-openblt.ld

projects/rfdsatt/eeprom.c

@@ -0,0 +1,125 @@
+#include <libopencm3/stm32/i2c.h>
+#include <errno.h>
+
+#include "eeprom.h"
+
+/* wait for I2C status register flags to appear */
+static bool i2c_wait(uint32_t i2c, uint32_t sr1, uint32_t sr2)
+{
+	unsigned int i;
+
+	for (i = 0; i < 1000000; i++) {
+		if (((I2C_SR1(i2c) & sr1) == sr1) &&
+		    ((I2C_SR2(i2c) & sr2) == sr2))
+			return true;
+	}
+	return false;
+}
+
+int eeprom_read(uint8_t *buf_out, unsigned int num_bytes, uint16_t read_addr)
+{
+	unsigned int i;
+
+	if (num_bytes > 255)
+		return -EINVAL; /* no reload cycles yet */
+
+	i2c_send_start(I2C1);
+
+	/* Wait for the end of the start condition, master mode selected, and BUSY bit set */
+	if (!i2c_wait(I2C1, I2C_SR1_SB, I2C_SR2_MSL|I2C_SR2_BUSY))
+		return -EIO;
+
+	/* Send Address, wait until it is transferred */
+	i2c_send_7bit_address(I2C1, 0x50, I2C_WRITE);
+	if (!i2c_wait(I2C1, I2C_SR1_ADDR, 0))
+		return -EIO;
+
+	/* Send memory address */
+#if 0 /* 16bit address */
+	i2c_send_data(I2C1, read_addr >> 8);
+	if (!i2c_wait(I2C1, I2C_SR1_BTF, 0))
+		return -EIO;
+#endif
+	i2c_send_data(I2C1, read_addr & 0xff);
+	if (!i2c_wait(I2C1, I2C_SR1_BTF, 0))
+		return -EIO;
+
+	/* re-start */
+	i2c_send_start(I2C1);
+	i2c_enable_ack(I2C1);
+
+	/* Wait for the end of the start condition, master mode selected, and BUSY bit set */
+	if (!i2c_wait(I2C1, I2C_SR1_SB, I2C_SR2_MSL|I2C_SR2_BUSY))
+		return -EIO;
+
+	/* Send Address, wait until it is transferred */
+	i2c_send_7bit_address(I2C1, 0x50, I2C_READ);
+	if (!i2c_wait(I2C1, I2C_SR1_ADDR, 0))
+		return -EIO;
+
+	for (i = 0; i < num_bytes; i++) {
+		if (i == num_bytes - 1)
+			i2c_disable_ack(I2C1);
+		if (!i2c_wait(I2C1, I2C_SR1_RxNE, 0))
+			return -EIO;
+		buf_out[i] = i2c_get_data(I2C1);
+	}
+
+	i2c_send_stop(I2C1);
+
+	return i;
+}
+
+static int wait_write_complete(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < 100; i++) {
+		i2c_send_start(I2C1);
+		/* Wait for the end of the start condition, master mode selected, and BUSY bit set */
+		if (!i2c_wait(I2C1, I2C_SR1_SB, I2C_SR2_MSL|I2C_SR2_BUSY))
+			return -EIO;
+		/* Send Address, wait until it is transferred */
+		i2c_send_7bit_address(I2C1, 0x50, I2C_WRITE);
+		if (i2c_wait(I2C1, I2C_SR1_ADDR, 0)) {
+			/* slave has sent an ACK, we may proceed */
+			return 0;
+		}
+		i2c_send_stop(I2C1);
+	}
+}
+
+int eeprom_write_byte(uint16_t write_addr, uint8_t byte)
+{
+	i2c_send_start(I2C1);
+
+	/* Wait for the end of the start condition, master mode selected, and BUSY bit set */
+	if (!i2c_wait(I2C1, I2C_SR1_SB, I2C_SR2_MSL|I2C_SR2_BUSY))
+		return -EIO;
+
+	/* Send Address, wait until it is transferred */
+	i2c_send_7bit_address(I2C1, 0x50, I2C_WRITE);
+	if (!i2c_wait(I2C1, I2C_SR1_ADDR, 0))
+		return -EIO;
+
+	/* Send memory address */
+#if 0 /* 16bit address */
+	i2c_send_data(I2C1, write_addr >> 8);
+	if (!i2c_wait(I2C1, I2C_SR1_BTF, 0))
+		return -EIO;
+#endif
+	i2c_send_data(I2C1, write_addr & 0xff);
+	if (!i2c_wait(I2C1, I2C_SR1_BTF, 0))
+		return -EIO;
+
+	/* Send data to write */
+	i2c_send_data(I2C1, byte);
+	if (!i2c_wait(I2C1, I2C_SR1_BTF, 0))
+		return -EIO;
+
+	i2c_send_stop(I2C1);
+
+	wait_write_complete();
+
+	return 1;
+}

projects/rfdsatt/eeprom.h

@@ -0,0 +1,5 @@
+#pragma once
+#include <stdint.h>
+
+int eeprom_read(uint8_t *buf_out, unsigned int num_bytes, uint16_t read_addr);
+int eeprom_write_byte(uint16_t write_addr, uint8_t byte);

projects/rfdsatt/rfdsatt.c

@@ -38,6 +38,7 @@
 #include <stdlib.h>
 
 #include "attenuator.h"
+#include "eeprom.h"
 #include "misc.h"
 
 static uint32_t last_reset_cause;
@@ -337,6 +338,36 @@ DEFUN(test, test_cmd, "test", "Enter interactive test-ramp mode")
 }
 
 
+DEFUN(i2c_read, i2c_read_cmd, "i2c-read", "Read from I2C EEPROM")
+{
+	uint16_t mem_addr = 0;
+	uint8_t rbuf[16];
+	unsigned int i;
+
+	i = eeprom_read(rbuf, sizeof(rbuf), mem_addr);
+	printf("Read result: %d\r\n", i);
+	for (i = 0; i < sizeof(rbuf); i++)
+		printf("%02x ", rbuf[i]);
+	printf("\r\n");
+}
+
+DEFUN(i2c_write, i2c_write_cmd, "i2c-write", "write to I2C EEPROM")
+{
+	int rc, addr, val;
+
+	if (argc < 3) {
+		printf("you have to specify address + value\r\n");
+		return;
+	}
+
+	addr = atoi(argv[1]);
+	val = atoi(argv[2]);
+
+	printf("Writing 0x%02x to address 0x%02x\r\n", val, addr);
+	rc = eeprom_write_byte(addr, val);
+	printf("Write result: %d\r\n", rc);
+}
+
 /***********************************************************************
  * main
  ***********************************************************************/
@@ -403,6 +434,8 @@ int main(void)
 	microvty_register(&att_set_cmd);
 	microvty_register(&interact_cmd);
 	microvty_register(&test_cmd);
+	microvty_register(&i2c_read_cmd);
+	microvty_register(&i2c_write_cmd);
 
 	print_banner();
 	microvty_print_prompt();