static void eventTask(ETSEvent *e)
{
if (e == NULL) {
return;
}
switch (e->sig)
{
case TWI_SIG_TX:
twi_onSlaveTransmit();
// if they didn't change buffer & length, initialize it
if (twi_txBufferLength == 0) {
twi_txBufferLength = 1;
twi_txBuffer[0] = 0x00;
}
// Initiate transmission
twi_onTwipEvent(TW_ST_DATA_ACK);
break;
case TWI_SIG_RX:
// ack future responses and leave slave receiver state
twi_releaseBus();
twi_onSlaveReceive(twi_rxBuffer, e->par);
break;
}
}
void ICACHE_RAM_ATTR onTimer()
{
twi_releaseBus();
twip_status = TW_BUS_ERROR;
twi_onTwipEvent(twip_status);
twip_mode = TWIPM_WAIT;
twip_state = TWIP_BUS_ERR;
}
void twi_irq_handle(void)
{
switch(TW_STATUS){
// All Master
case TW_START: // sent start condition
case TW_REP_START: // sent repeated start condition
// copy device address and r/w bit to output register and ack
TWDR = twi_slarw;
twi_reply(1);
break;
// Master Transmitter
case TW_MT_SLA_ACK: // slave receiver acked address
case TW_MT_DATA_ACK: // slave receiver acked data
// if there is data to send, send it, otherwise stop
if(twi_masterBufferIndex < twi_masterBufferLength){
// copy data to output register and ack
TWDR = twi_masterBuffer[twi_masterBufferIndex++];
twi_reply(1);
}else{
twi_stop();
}
break;
case TW_MT_SLA_NACK: // address sent, nack received
twi_error = TW_MT_SLA_NACK;
twi_stop();
break;
case TW_MT_DATA_NACK: // data sent, nack received
twi_error = TW_MT_DATA_NACK;
twi_stop();
break;
case TW_MT_ARB_LOST: // lost bus arbitration
twi_error = TW_MT_ARB_LOST;
twi_releaseBus();
break;
// Master Receiver
case TW_MR_DATA_ACK: // data received, ack sent
// put byte into buffer
twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
case TW_MR_SLA_ACK: // address sent, ack received
// ack if more bytes are expected, otherwise nack
if(twi_masterBufferIndex < twi_masterBufferLength){
twi_reply(1);
}else{
twi_reply(0);
}
break;
case TW_MR_DATA_NACK: // data received, nack sent
// put final byte into buffer
twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
case TW_MR_SLA_NACK: // address sent, nack received
twi_stop();
break;
// TW_MR_ARB_LOST handled by TW_MT_ARB_LOST case
// Slave Receiver
case TW_SR_SLA_ACK: // addressed, returned ack
case TW_SR_GCALL_ACK: // addressed generally, returned ack
case TW_SR_ARB_LOST_SLA_ACK: // lost arbitration, returned ack
case TW_SR_ARB_LOST_GCALL_ACK: // lost arbitration, returned ack
// enter slave receiver mode
twi_state = TWI_SRX;
// indicate that rx buffer can be overwritten and ack
twi_rxBufferIndex = 0;
twi_reply(1);
break;
case TW_SR_DATA_ACK: // data received, returned ack
case TW_SR_GCALL_DATA_ACK: // data received generally, returned ack
// if there is still room in the rx buffer
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
// put byte in buffer and ack
twi_rxBuffer[twi_rxBufferIndex++] = TWDR;
twi_reply(1);
}else{
// otherwise nack
twi_reply(0);
}
break;
case TW_SR_STOP: // stop or repeated start condition received
// put a null char after data if there's room
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
twi_rxBuffer[twi_rxBufferIndex] = '\0';
}
// callback to user defined callback
twi_onSlaveReceive(twi_rxBuffer, twi_rxBufferIndex);
// ack future responses
twi_reply(1);
// leave slave receiver state
twi_state = TWI_READY;
break;
case TW_SR_DATA_NACK: // data received, returned nack
case TW_SR_GCALL_DATA_NACK: // data received generally, returned nack
// nack back at master
twi_reply(0);
break;
// Slave Transmitter
case TW_ST_SLA_ACK: // addressed, returned ack
case TW_ST_ARB_LOST_SLA_ACK: // arbitration lost, returned ack
// enter slave transmitter mode
twi_state = TWI_STX;
// ready the tx buffer index for iteration
twi_txBufferIndex = 0;
// set tx buffer length to be zero, to verify if user changes it
twi_txBufferLength = 0;
// request for txBuffer to be filled and length to be set
// note: user must call twi_transmit(bytes, length) to do this
twi_onSlaveTransmit();
// if they didn't change buffer & length, initialize it
if(0 == twi_txBufferLength){
twi_txBufferLength = 1;
twi_txBuffer[0] = 0x00;
}
// transmit first byte from buffer, fall
case TW_ST_DATA_ACK: // byte sent, ack returned
// copy data to output register
TWDR = twi_txBuffer[twi_txBufferIndex++];
// if there is more to send, ack, otherwise nack
if(twi_txBufferIndex < twi_txBufferLength){
twi_reply(1);
}else{
twi_reply(0);
}
break;
case TW_ST_DATA_NACK: // received nack, we are done
case TW_ST_LAST_DATA: // received ack, but we are done already!
// ack future responses
twi_reply(1);
// leave slave receiver state
twi_state = TWI_READY;
break;
// All
case TW_NO_INFO: // no state information
break;
case TW_BUS_ERROR: // bus error, illegal stop/start
twi_error = TW_BUS_ERROR;
twi_stop();
break;
}
}
/*
* Function twi_writeTo
* Desc attempts to become twi bus master and write a
* series of bytes to a device on the bus
* Input address: 7bit i2c device address
* data: pointer to byte array
* length: number of bytes in array
* wait: boolean indicating to wait for write or not
* Output 0 .. success
* 1 .. length to long for buffer
* 2 .. address send, NACK received
* 3 .. data send, NACK received
* 4 .. other twi error (lost bus arbitration, bus error, ..)
*/
uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait)
{
uint8_t i;
// ensure data will fit into buffer
if(TWI_BUFFER_LENGTH < length){
return 1;
}
// Prepare timeout feature
if (locking_timeout > 0) {
millis_start = millis();
did_timeout = 0;
}
// wait until twi is ready, become master transmitter
while(TWI_READY != twi_state){
// Test for timeout
if (locking_timeout > 0 && (millis() - millis_start) > locking_timeout) {
did_timeout = 1;
twi_releaseBus();
return(4); // based on what you see below, this is "other twi error"
}
continue;
}
twi_state = TWI_MTX;
// reset error state (0xFF.. no error occured)
twi_error = 0xFF;
// initialize buffer iteration vars
twi_masterBufferIndex = 0;
twi_masterBufferLength = length;
// copy data to twi buffer
for(i = 0; i < length; ++i){
twi_masterBuffer[i] = data[i];
}
// build sla+w, slave device address + w bit
twi_slarw = TW_WRITE;
twi_slarw |= address << 1;
// send start condition
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
// Prepare timeout feature
if (locking_timeout > 0) {
millis_start = millis();
did_timeout = 0;
}
// wait for write operation to complete
while(wait && (TWI_MTX == twi_state)){
// Test for timeout
if (locking_timeout > 0 && (millis() - millis_start) > locking_timeout) {
did_timeout = 1;
twi_releaseBus();
return(4); // based on what you see below, this is "other twi error"
}
continue;
}
if (twi_error == 0xFF)
return 0; // success
else if (twi_error == TW_MT_SLA_NACK)
return 2; // error: address send, nack received
else if (twi_error == TW_MT_DATA_NACK)
return 3; // error: data send, nack received
else
return 4; // other twi error
}
/*
* Function twi_readFrom
* Desc attempts to become twi bus master and read a
* series of bytes from a device on the bus
* Input address: 7bit i2c device address
* data: pointer to byte array
* length: number of bytes to read into array
* Output number of bytes read
*/
uint8_t twi_readFrom(uint8_t address, uint8_t* data, uint8_t length)
{
uint8_t i;
// ensure data will fit into buffer
if(TWI_BUFFER_LENGTH < length){
return 0;
}
// Prepare timeout feature
if (locking_timeout > 0) {
millis_start = millis();
did_timeout = 0;
}
// wait until twi is ready, become master receiver
while(TWI_READY != twi_state){
// Test for timeout
if (locking_timeout > 0 && (millis() - millis_start) > locking_timeout) {
did_timeout = 1;
twi_releaseBus();
return(0); // never became ready in time, let's bail.
}
continue;
}
twi_state = TWI_MRX;
// reset error state (0xFF.. no error occured)
twi_error = 0xFF;
// initialize buffer iteration vars
twi_masterBufferIndex = 0;
twi_masterBufferLength = length-1; // This is not intuitive, read on...
// On receive, the previously configured ACK/NACK setting is transmitted in
// response to the received byte before the interrupt is signalled.
// Therefor we must actually set NACK when the _next_ to last byte is
// received, causing that NACK to be sent in response to receiving the last
// expected byte of data.
// build sla+w, slave device address + w bit
twi_slarw = TW_READ;
twi_slarw |= address << 1;
// send start condition
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
// Prepare timeout feature
if (locking_timeout > 0) {
millis_start = millis();
did_timeout = 0;
}
// wait for read operation to complete
while(TWI_MRX == twi_state){
// Test for timeout
if (locking_timeout > 0 && (millis() - millis_start) > locking_timeout) {
did_timeout = 1;
// Read operation didn't complete in time, remote end is probably dead; release bus and bail
twi_releaseBus();
return(0);
}
continue;
}
if (twi_masterBufferIndex < length)
length = twi_masterBufferIndex;
// copy twi buffer to data
for(i = 0; i < length; ++i){
data[i] = twi_masterBuffer[i];
}
return length;
}
void ICACHE_RAM_ATTR twi_onTwipEvent(uint8_t status)
{
switch(status) {
// Slave Receiver
case TW_SR_SLA_ACK: // addressed, returned ack
case TW_SR_GCALL_ACK: // addressed generally, returned ack
case TW_SR_ARB_LOST_SLA_ACK: // lost arbitration, returned ack
case TW_SR_ARB_LOST_GCALL_ACK: // lost arbitration, returned ack
// enter slave receiver mode
twi_state = TWI_SRX;
// indicate that rx buffer can be overwritten and ack
twi_rxBufferIndex = 0;
twi_reply(1);
break;
case TW_SR_DATA_ACK: // data received, returned ack
case TW_SR_GCALL_DATA_ACK: // data received generally, returned ack
// if there is still room in the rx buffer
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
// put byte in buffer and ack
twi_rxBuffer[twi_rxBufferIndex++] = TWDR;
twi_reply(1);
}else{
// otherwise nack
twi_reply(0);
}
break;
case TW_SR_STOP: // stop or repeated start condition received
// put a null char after data if there's room
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
twi_rxBuffer[twi_rxBufferIndex] = '\0';
}
// callback to user-defined callback over event task to allow for non-RAM-residing code
//twi_rxBufferLock = true; // This may be necessary
ets_post(EVENTTASK_QUEUE_PRIO, TWI_SIG_RX, twi_rxBufferIndex);
// since we submit rx buffer to "wire" library, we can reset it
twi_rxBufferIndex = 0;
break;
case TW_SR_DATA_NACK: // data received, returned nack
case TW_SR_GCALL_DATA_NACK: // data received generally, returned nack
// nack back at master
twi_reply(0);
break;
// Slave Transmitter
case TW_ST_SLA_ACK: // addressed, returned ack
case TW_ST_ARB_LOST_SLA_ACK: // arbitration lost, returned ack
// enter slave transmitter mode
twi_state = TWI_STX;
// ready the tx buffer index for iteration
twi_txBufferIndex = 0;
// set tx buffer length to be zero, to verify if user changes it
twi_txBufferLength = 0;
// callback to user-defined callback over event task to allow for non-RAM-residing code
// request for txBuffer to be filled and length to be set
// note: user must call twi_transmit(bytes, length) to do this
ets_post(EVENTTASK_QUEUE_PRIO, TWI_SIG_TX, 0);
break;
case TW_ST_DATA_ACK: // byte sent, ack returned
// copy data to output register
TWDR = twi_txBuffer[twi_txBufferIndex++];
bitCount = 8;
bitCount--;
(twi_data & 0x80) ? SDA_HIGH() : SDA_LOW();
twi_data <<= 1;
// if there is more to send, ack, otherwise nack
if(twi_txBufferIndex < twi_txBufferLength){
twi_reply(1);
}else{
twi_reply(0);
}
break;
case TW_ST_DATA_NACK: // received nack, we are done
case TW_ST_LAST_DATA: // received ack, but we are done already!
// leave slave receiver state
twi_releaseBus();
break;
// All
case TW_NO_INFO: // no state information
break;
case TW_BUS_ERROR: // bus error, illegal stop/start
twi_error = TW_BUS_ERROR;
twi_stop();
break;
}
}
