uint8_t TwoWire::endTransmission(uint8_t sendStop)
{
//printf("\nendTransmission %d (%x %x %x) %x\n", txBufferLength,txBuffer[0], txBuffer[1], txBuffer[2], sendStop);
uint32_t i=0, len, status;
len = txBufferLength;
if (!len) return 4; // no data to transmit
// wait while bus is busy
while (1) {
status = port->MSR; // pg 2899 & 2892
if (!(status & LPI2C_MSR_BBF)) break; // bus is available
if (status & LPI2C_MSR_MBF) break; // we already have bus control
// TODO: timeout...
}
//printf("m=%x\n", status);
// Wonder if MFSR we should maybe clear it?
if ( port->MFSR & 0x7) {
port->MCR = LPI2C_MCR_MEN | LPI2C_MCR_RTF; // clear the FIFO
port->MSR = LPI2C_MSR_PLTF | LPI2C_MSR_ALF | LPI2C_MSR_NDF | LPI2C_MSR_SDF | LPI2C_MSR_FEF; // clear flags
//printf("Clear TX Fifo %lx %lx\n", port->MSR, port->MFSR);
}
// TODO: is this correct if the prior use didn't send stop?
//port->MSR = LPI2C_MSR_PLTF | LPI2C_MSR_ALF | LPI2C_MSR_NDF | LPI2C_MSR_SDF; // clear flags
port->MSR = status;
//printf("MSR=%lX, MFSR=%lX\n", status, port->MFSR);
//elapsedMillis timeout=0;
while (1) {
// transmit stuff, if we haven't already
if (i <= len) {
uint32_t fifo_used = port->MFSR & 0x07; // pg 2914
//if (fifo_used < 4) printf("t=%ld\n", fifo_used);
while (fifo_used < 4) {
if (i == 0) {
//printf("start %x\n", txBuffer[0]);
port->MTDR = LPI2C_MTDR_CMD_START | txBuffer[0];
i = 1;
} else if (i < len) {
port->MTDR = LPI2C_MTDR_CMD_TRANSMIT | txBuffer[i++];
} else {
if (sendStop) port->MTDR = LPI2C_MTDR_CMD_STOP;
i++;
break;
}
fifo_used = fifo_used + 1;
}
}
// monitor status
status = port->MSR; // pg 2899 & 2892
if (status & LPI2C_MSR_ALF) {
//printf("arbitration lost\n");
return 4; // we lost bus arbitration to another master
}
if (status & LPI2C_MSR_NDF) {
//printf("NACK, f=%d, i=%d\n", port->MFSR & 0x07, i);
// TODO: check that hardware really sends stop automatically
port->MCR = LPI2C_MCR_MEN | LPI2C_MCR_RTF; // clear the FIFO
// TODO: is always sending a stop the right way to recover?
port->MTDR = LPI2C_MTDR_CMD_STOP;
return 2; // NACK for address
//return 3; // NACK for data TODO: how to discern addr from data?
}
//if (status & LPI2C_MSR_PLTF) {
//printf("bus stuck - what to do?\n");
//return 4;
//}
//if (timeout > 100) {
//printf("status = %x\n", status);
//timeout = 0;
//}
if (sendStop) {
if (status & LPI2C_MSR_SDF) {
// master automatically sends stop condition on some
// types of errors, so this flag only means success
// when all comments in fifo have been fully used
uint32_t fifo = port->MFSR & 0x07;
if (fifo == 0) return 0;
}
} else {
uint32_t fifo_used = port->MFSR & 0x07; // pg 2914
if (fifo_used == 0) {
//digitalWriteFast(15, HIGH);
//delayMicroseconds(2);
//digitalWriteFast(15, LOW);
// TODO: this returns before the last data transmits!
// Should verify every byte ACKs, arbitration not lost
//printf("fifo empty, msr=%x\n", status);
return 0;
}
}
}
}
uint8_t TwoWire::requestFrom(uint8_t address, uint8_t length, uint8_t sendStop)
{
uint32_t cmd=0, status, fifo;
// wait while bus is busy
//printf("\nrequestFrom %x %x %x\n", address, length, sendStop);
while (1) {
status = port->MSR; // pg 2899 & 2892
if (!(status & LPI2C_MSR_BBF)) break; // bus is available
if (status & LPI2C_MSR_MBF) break; // we already have bus control
// TODO: timeout...
}
//printf("idle2, msr=%x\n", status);
// TODO: is this correct if the prior use didn't send stop?
port->MSR = LPI2C_MSR_PLTF | LPI2C_MSR_ALF | LPI2C_MSR_NDF | LPI2C_MSR_SDF | LPI2C_MSR_FEF; // clear flags
//printf("MSR=%lX, MCR:%lx, MFSR=%lX\n", status, port->MCR, port->MFSR);
// Wonder if MFSR we should maybe clear it?
if ( port->MFSR & 0x7) {
port->MCR = LPI2C_MCR_MEN | LPI2C_MCR_RTF; // clear the FIFO
port->MSR = LPI2C_MSR_PLTF | LPI2C_MSR_ALF | LPI2C_MSR_NDF | LPI2C_MSR_SDF | LPI2C_MSR_FEF; // clear flags
//printf("Clear TX Fifo %lx %lx\n", port->MSR, port->MFSR);
}
address = (address & 0x7F) << 1;
if (length < 1) length = 1;
if (length > 255) length = 255;
rxBufferIndex = 0;
rxBufferLength = 0;
//elapsedMillis timeout=0;
while (1) {
// transmit stuff, if we haven't already
if (cmd < 3) {
fifo = port->MFSR & 0x07; // pg 2914
//if (fifo < 4) printf("t=%ld\n", fifo);
while (fifo < 4 && cmd < 3) {
if (cmd == 0) {
port->MTDR = LPI2C_MTDR_CMD_START | 1 | address;
} else if (cmd == 1) {
// causes bus stuck... need way to recover
//port->MTDR = LPI2C_MTDR_CMD_START | (length - 1);
port->MTDR = LPI2C_MTDR_CMD_RECEIVE | (length - 1);
} else {
if (sendStop) port->MTDR = LPI2C_MTDR_CMD_STOP;
}
cmd++;
fifo = fifo + 1;
}
}
// receive stuff
if (rxBufferLength < sizeof(rxBuffer)) {
fifo = (port->MFSR >> 16) & 0x07;
//if (fifo > 0) printf("r=%ld\n", fifo);
while (fifo > 0 && rxBufferLength < sizeof(rxBuffer)) {
rxBuffer[rxBufferLength++] = port->MRDR;
fifo = fifo - 1;
}
}
// monitor status
status = port->MSR; // pg 2899 & 2892
if (status & LPI2C_MSR_ALF) {
//printf("arbitration lost\n");
break;
}
if (status & LPI2C_MSR_NDF) {
//printf("got NACK\n");
// TODO: how to make sure stop is sent?
break;
}
//if (timeout > 250) {
//printf("Status = %x\n", status);
//timeout = 0;
//}
if (rxBufferLength >= length && cmd >= 3) break;
}
//digitalWriteFast(15, HIGH);
//delayMicroseconds(2);
//digitalWriteFast(15, LOW);
return rxBufferLength;
}