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Fix I2C bit banging code

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This commit is contained in:
Ondrej Jirman 2021-09-05 01:57:58 +02:00
parent bf0c0e9c97
commit 0b280ebc14
1 changed files with 23 additions and 12 deletions
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35
firmware/main.c
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@ -968,25 +968,30 @@ static void self_test_run(void)
#define CHARGER_ADDR 0x75u #define CHARGER_ADDR 0x75u
// Inspired by: https://calcium3000.wordpress.com/2016/08/19/i2c-bit-banging-tutorial-part-i/ // Inspired by: https://calcium3000.wordpress.com/2016/08/19/i2c-bit-banging-tutorial-part-i/
// TODO: recognize clock-stretching // TODO: recognize clock-stretching (probably not necessary, charger doesn't use it)
#define CHG_SCL BIT(5) #define CHG_SCL BIT(5)
#define CHG_SDA BIT(6) #define CHG_SDA BIT(6)
#define CHG_INT BIT(7) #define CHG_INT BIT(7)
#define CHG_PORT P8 #define CHG_PORT P8
#define CHG_RELEASE_SCL P0_P8M0 &= ~CHG_SCL #define CHG_RELEASE_SCL P0_P8M0 |= CHG_SCL
#define CHG_PULL_SCL P0_P8M0 |= CHG_SCL #define CHG_PULL_SCL P0_P8M0 &= ~CHG_SCL
#define CHG_RELEASE_SDA P0_P8M0 &= ~CHG_SDA #define CHG_RELEASE_SDA P0_P8M0 |= CHG_SDA
#define CHG_PULL_SDA P0_P8M0 |= CHG_SDA #define CHG_PULL_SDA P0_P8M0 &= ~CHG_SDA
void i2c_init(void) void i2c_init(void)
{ {
PAGESW = 1;
P1_PHCON2 |= BIT(3);
PAGESW = 0; PAGESW = 0;
P0_P8M0 |= CHG_SCL | CHG_SDA | CHG_INT; // set SCL/SDA to input (release I2C bus) P0_P8M0 |= CHG_SCL | CHG_SDA | CHG_INT; // set SCL/SDA to input (release I2C bus)
P8 &= ~(CHG_SCL | CHG_SDA); // set SCL/SDA to output low when changed to output mode P8 &= ~(CHG_SCL | CHG_SDA); // set SCL/SDA to output low when changed to output mode
} }
/*
// returns 1 on busy/timeout, abort needed because the bus is locked // returns 1 on busy/timeout, abort needed because the bus is locked
static __bit poll_scl_busy(void) static __bit poll_scl_busy(void)
{ {
@ -999,13 +1004,16 @@ static __bit poll_scl_busy(void)
return 1; return 1;
} }
*/
void i2c_start_condition(void) void i2c_start_condition(void)
{ {
CHG_RELEASE_SCL;
CHG_RELEASE_SDA; CHG_RELEASE_SDA;
delay_us(5); delay_us(5);
CHG_RELEASE_SCL;
delay_us(5);
CHG_PULL_SDA; CHG_PULL_SDA;
delay_us(5); delay_us(5);
@ -1031,12 +1039,13 @@ void i2c_write_bit(__bit b)
CHG_RELEASE_SDA; CHG_RELEASE_SDA;
else else
CHG_PULL_SDA; CHG_PULL_SDA;
delay_us(1);
delay_us(5);
CHG_RELEASE_SCL; CHG_RELEASE_SCL;
delay_us(5); delay_us(5);
CHG_PULL_SCL; CHG_PULL_SCL;
delay_us(1);
} }
__bit i2c_read_bit(void) __bit i2c_read_bit(void)
@ -1044,10 +1053,9 @@ __bit i2c_read_bit(void)
__bit b; __bit b;
CHG_RELEASE_SDA; CHG_RELEASE_SDA;
delay_us(5);
CHG_RELEASE_SCL; CHG_RELEASE_SCL;
delay_us(5); delay_us(4);
if (CHG_PORT & CHG_SDA) if (CHG_PORT & CHG_SDA)
b = 1; b = 1;
@ -1055,6 +1063,7 @@ __bit i2c_read_bit(void)
b = 0; b = 0;
CHG_PULL_SCL; CHG_PULL_SCL;
delay_us(2);
return b; return b;
} }
@ -1070,7 +1079,7 @@ __bit i2c_write_byte(uint8_t data)
} }
// read ack bit // read ack bit
return i2c_read_bit(); return !i2c_read_bit();
} }
uint8_t i2c_read_byte(__bit ack) uint8_t i2c_read_byte(__bit ack)
@ -1142,7 +1151,7 @@ stop:
static __bit charger_is_woke(void) static __bit charger_is_woke(void)
{ {
return !P87; return P87;
} }
static uint8_t charger_read(void) static uint8_t charger_read(void)
@ -1194,8 +1203,10 @@ static void exec_system_command(void)
jump_to_usb_bootloader = 1; jump_to_usb_bootloader = 1;
} else if (REG_SYS(COMMAND) == REG_SYS_COMMAND_CHG_READ) { } else if (REG_SYS(COMMAND) == REG_SYS_COMMAND_CHG_READ) {
REG_SYS(COMMAND) = charger_read(); REG_SYS(COMMAND) = charger_read();
goto out_done;
} else if (REG_SYS(COMMAND) == REG_SYS_COMMAND_CHG_WRITE) { } else if (REG_SYS(COMMAND) == REG_SYS_COMMAND_CHG_WRITE) {
REG_SYS(COMMAND) = charger_write(); REG_SYS(COMMAND) = charger_write();
goto out_done;
} else { } else {
REG_SYS(COMMAND) = 0xff; REG_SYS(COMMAND) = 0xff;
goto out_done; goto out_done;