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swi2c safe init

This commit is contained in:
Alex Voinea 2022-02-25 18:59:56 +01:00 committed by D.R.racer
parent 8b9bb23652
commit 54b98c4e63
1 changed files with 49 additions and 19 deletions
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68
Firmware/swi2c.c
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@ -15,23 +15,41 @@
#define SWI2C_ASHF 0x01 //address shift (<< 1)
#define SWI2C_DMSK 0x7f //device address mask
static void __delay(void);
static void swi2c_start(void);
static void swi2c_stop(void);
// static void swi2c_ack(void);
static void swi2c_nack(void);
static uint8_t swi2c_wait_ack();
static uint8_t swi2c_read(void);
static void swi2c_write(uint8_t data);
void __delay(void)
void swi2c_init(void)
{
SET_INPUT(SWI2C_SDA);
WRITE(SWI2C_SDA, 1); //SDA must be input with pullups while we are not sure if the slave is outputing or not
WRITE(SWI2C_SCL, 1);
SET_OUTPUT(SWI2C_SCL); //SCL can be an output at all times. The bus is not in a multi-master configuration.
for (uint8_t i = 0; i < 100; i++) //wait. Not sure what for, but wait anyway.
__delay();
for (uint8_t i = 0; i < 10; i++) { //send nack 10 times. This makes sure that the slave gets a nack regardless of it's state when we init the bus.
swi2c_nack();
}
swi2c_stop(); //"release" the bus by sending a stop condition.
SET_OUTPUT(SWI2C_SDA); //finally make the SDA line an output since the bus is idle for sure.
}
static void __delay(void)
{
_delay_us(1.5);
}
void swi2c_init(void)
{
WRITE(SWI2C_SDA, 1);
WRITE(SWI2C_SCL, 1);
SET_OUTPUT(SWI2C_SDA);
SET_OUTPUT(SWI2C_SCL);
uint8_t i; for (i = 0; i < 100; i++)
__delay();
}
void swi2c_start(void)
static void swi2c_start(void)
{
WRITE(SWI2C_SDA, 0);
__delay();
@ -39,7 +57,7 @@ void swi2c_start(void)
__delay();
}
void swi2c_stop(void)
static void swi2c_stop(void)
{
WRITE(SWI2C_SCL, 1);
__delay();
@ -47,7 +65,8 @@ void swi2c_stop(void)
__delay();
}
void swi2c_ack(void)
/*
static void swi2c_ack(void)
{
WRITE(SWI2C_SDA, 0);
__delay();
@ -56,8 +75,19 @@ void swi2c_ack(void)
WRITE(SWI2C_SCL, 0);
__delay();
}
*/
uint8_t swi2c_wait_ack()
static void swi2c_nack(void)
{
WRITE(SWI2C_SDA, 1);
__delay();
WRITE(SWI2C_SCL, 1);
__delay();
WRITE(SWI2C_SCL, 0);
__delay();
}
static uint8_t swi2c_wait_ack()
{
SET_INPUT(SWI2C_SDA);
__delay();
@ -77,13 +107,13 @@ uint8_t swi2c_wait_ack()
return ack;
}
uint8_t swi2c_read(void)
static uint8_t swi2c_read(void)
{
WRITE(SWI2C_SDA, 1);
__delay();
SET_INPUT(SWI2C_SDA);
uint8_t data = 0;
int8_t bit; for (bit = 7; bit >= 0; bit--)
for (uint8_t bit = 8; bit-- > 0;)
{
WRITE(SWI2C_SCL, 1);
__delay();
@ -95,9 +125,9 @@ uint8_t swi2c_read(void)
return data;
}
void swi2c_write(uint8_t data)
static void swi2c_write(uint8_t data)
{
int8_t bit; for (bit = 7; bit >= 0; bit--)
for (uint8_t bit = 8; bit-- > 0;)
{
WRITE(SWI2C_SDA, data & _BV(bit));
__delay();