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Update I2CManager_STM32.h

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Remove debug code (writing to pin D2).  Update comments.  Restructure.
This commit is contained in:
Neil McKechnie 2023-03-30 18:30:38 +01:00
parent 4f56837d28
commit 4f43a413b5
1 changed files with 39 additions and 34 deletions
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73
I2CManager_STM32.h
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@ -238,6 +238,8 @@ void I2CManagerClass::I2C_sendStart() {
// and the STOP bit is already set, we could output multiple STOP conditions.
while (s->CR1 & I2C_CR1_STOP) {} // Wait for STOP bit to reset
s->CR2 |= (I2C_CR2_ITEVTEN | I2C_CR2_ITERREN); // Enable interrupts
s->CR2 &= ~I2C_CR2_ITBUFEN; // Don't enable buffer interupts yet.
s->CR1 &= ~I2C_CR1_POS; // Clear the POS bit
s->CR1 |= (I2C_CR1_ACK | I2C_CR1_START); // Enable the ACK and generate START
transactionState = TS_START;
@ -248,7 +250,6 @@ void I2CManagerClass::I2C_sendStart() {
***************************************************************************/
void I2CManagerClass::I2C_sendStop() {
s->CR1 |= I2C_CR1_STOP; // Stop I2C
//while (s->CR1 & I2C_CR1_STOP) {} // Wait for STOP bit to reset
}
/***************************************************************************
@ -261,7 +262,7 @@ void I2CManagerClass::I2C_close() {
// Should never happen, but wait for up to 500us only.
unsigned long startTime = micros();
while ((s->CR1 & I2C_CR1_PE) != 0) {
if (micros() - startTime >= 500UL) break;
if ((int32_t)(micros() - startTime) >= 500) break;
}
NVIC_DisableIRQ(I2C1_EV_IRQn);
NVIC_DisableIRQ(I2C1_ER_IRQn);
@ -275,9 +276,6 @@ void I2CManagerClass::I2C_close() {
void I2CManagerClass::I2C_handleInterrupt() {
volatile uint16_t temp_sr1, temp_sr2;
pinMode(D2, OUTPUT);
digitalWrite(D2, 1);
temp_sr1 = s->SR1;
// Check for errors first
@ -330,8 +328,8 @@ void I2CManagerClass::I2C_handleInterrupt() {
break;
case TS_W_ADDR:
temp_sr2 = s->SR2; // read SR2 to complete clearing the ADDR bit
if (temp_sr1 & I2C_SR1_ADDR) {
temp_sr2 = s->SR2; // read SR2 to complete clearing the ADDR bit
// Event EV6
// Address sent successfully, device has ack'd in response.
if (!bytesToSend) {
@ -340,60 +338,65 @@ void I2CManagerClass::I2C_handleInterrupt() {
completionStatus = I2C_STATUS_OK;
state = I2C_STATE_COMPLETED;
} else {
if (bytesToSend <= 2) {
// After this interrupt, we will have no more data to send.
// Next event of interest will be the BTF interrupt, so disable TXE interrupt
s->CR2 &= ~I2C_CR2_ITBUFEN;
transactionState = TS_W_STOP;
} else {
// More data to send, enable TXE interrupt.
s->CR2 |= I2C_CR2_ITBUFEN;
transactionState = TS_W_DATA;
}
// Put one or two bytes into DR to avoid interrupts
// Put one byte into DR to load shift register.
s->DR = sendBuffer[txCount++];
bytesToSend--;
if (bytesToSend) {
// Put another byte to load DR
s->DR = sendBuffer[txCount++];
bytesToSend--;
}
if (!bytesToSend) {
// No more bytes to send.
// The TXE interrupt occurs when the DR is empty, and the BTF interrupt
// occurs when the shift register is also empty (one character later).
// To avoid repeated TXE interrupts during this time, we disable TXE interrupt.
s->CR2 &= ~I2C_CR2_ITBUFEN; // Wait for BTF interrupt, disable TXE interrupt
transactionState = TS_W_STOP;
} else {
// More data remaining to send after this interrupt, enable TXE interrupt.
s->CR2 |= I2C_CR2_ITBUFEN;
transactionState = TS_W_DATA;
}
}
}
break;
case TS_W_DATA:
if (temp_sr1 & I2C_SR1_TXE) {
// Event EV8_1/EV8/EV8_2
// Event EV8_1/EV8
// Transmitter empty, write a byte to it.
if (bytesToSend) {
if (bytesToSend == 1) {
// We will next need to wait for BTF.
// TXE becomes set one byte before BTF is set, so disable
// TXE interrupt while we're waiting for BTF, to suppress
// repeated interrupts during that period.
s->CR2 &= ~I2C_CR2_ITBUFEN;
transactionState = TS_W_STOP;
}
s->DR = sendBuffer[txCount++];
bytesToSend--;
if (!bytesToSend) {
s->CR2 &= ~I2C_CR2_ITBUFEN; // Disable TXE interrupt
transactionState = TS_W_STOP;
}
}
}
}
break;
case TS_W_STOP:
if ((temp_sr1 & I2C_SR1_BTF) && (temp_sr1 & I2C_SR1_TXE)) {
if (temp_sr1 & I2C_SR1_BTF) {
// Event EV8_2
// All writes finished.
// Done, last character sent. Anything to receive?
if (bytesToReceive) {
// Start a read operation by sending (re)start
I2C_sendStart();
I2C_sendStart();
// NOTE: Three redundant BTF interrupts take place between the
// first BTF interrupt and the START interrupt. I've tried all sorts
// of ways to eliminate them, and the only thing that worked for
// me was to loop until the BTF bit becomes reset. Either way,
// it's a waste of processor time. Anyone got a solution?
//while (s->SR1 && I2C_SR1_BTF) {}
transactionState = TS_START;
} else {
// Done.
I2C_sendStop();
transactionState = TS_IDLE;
completionStatus = I2C_STATUS_OK;
state = I2C_STATE_COMPLETED;
}
s->SR1 &= I2C_SR1_BTF; // Clear BTF interrupt
}
break;
@ -477,9 +480,11 @@ void I2CManagerClass::I2C_handleInterrupt() {
}
break;
}
// If we've received an interrupt at any other time, we're not interested so clear it
// to prevent it recurring ad infinitum.
s->SR1 = 0;
}
delayMicroseconds(1);
digitalWrite(D2, 0);
}
#endif /* I2CMANAGER_STM32_H */