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Fix I2C STOP-condition, now also working in case of late ACK or NACK.

pull/55/merge
guido 2021-05-31 13:46:59 +02:00
rodzic 94204bd3bd
commit f632dac0a9
1 zmienionych plików z 6 dodań i 5 usunięć
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11
QCX-SSB.ino
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@ -454,8 +454,8 @@ public:
#define _I2C_SCL_HI() DDRD &= ~_I2C_SCL; _DELAY();
#define _I2C_SCL_LO() DDRD |= _I2C_SCL; _DELAY();
#endif // !OLED_I2C_DIRECT_IO
#define _I2C_START() _I2C_SDA_LO(); _I2C_SCL_LO(); _I2C_SDA_HI();
#define _I2C_STOP() _I2C_SCL_HI(); _I2C_SDA_HI();
#define _I2C_START() _I2C_SDA_LO(); _I2C_SCL_LO(); // _I2C_SDA_HI();
#define _I2C_STOP() _I2C_SDA_LO(); _I2C_SCL_HI(); _I2C_SDA_HI();
#define _I2C_SUSPEND() //_I2C_SDA_LO(); // SDA_LO to allow re-use as output port
#define _SendBit(data, bit) \
if(data & 1 << bit){ \
@ -1117,6 +1117,7 @@ ISR(PCINT2_vect){ // Interrupt on rotary encoder turn
// I2C communication starts with a START condition, multiple single byte-transfers (MSB first) followed by an ACK/NACK and stops with a STOP condition;
// during data-transfer SDA may only change when SCL is LOW, during a START/STOP condition SCL is HIGH and SDA goes DOWN for a START and UP for a STOP.
// https://www.ti.com/lit/an/slva704/slva704.pdf
class I2C {
public:
#if(F_MCU > 20900000)
@ -1159,6 +1160,7 @@ public:
I2C_SDA_HI();
}
inline void stop(){
I2C_SDA_LO(); // ensure SDA is LO so STOP-condition can be initiated by pulling SCL HI (in case of ACK it SDA was already LO, but for a delayed ACK or NACK it is not!)
I2C_SCL_HI();
I2C_SDA_HI();
I2C_DDR &= ~(I2C_SDA | I2C_SCL); // prepare for a start: pull-up both SDA, SCL
@ -1196,11 +1198,10 @@ public:
SendBit(data, 1 << 2);
SendBit(data, 1 << 1);
SendBit(data, 1 << 0);
SendBit( 0, 1 << 0); // ACK/NAK: instead of assuming slave will set SDA is LOW (ACK), force SDA is LOW so that at least STOP condition will succeed (in case ACK is delayed, e.g. with MCP23008).
/*I2C_SDA_HI(); // recv ACK
I2C_SDA_HI(); // recv ACK
DELAY(I2C_DELAY);
I2C_SCL_HI();
I2C_SCL_LO();*/
I2C_SCL_LO();
}
inline uint8_t RecvBit(uint8_t mask){
I2C_SCL_HI();