Today I ran into an issue while implementing a PMBus interface on an Arduino every.
PMBus derrives from SMBus which uses I2C and ultimately TWI.
From System Management Bus Specification Version 3.3:
This requires a 0 byte read or write transaction where the read is currently not possible with this implementation as the write bit is implicitly set in both cases.
Both cases result in a call to
uint8_t TWI_MasterWriteRead(uint8_t slave_address,
uint8_t *write_data,
uint8_t bytes_to_write,
uint8_t bytes_to_read,
uint8_t send_stop)
with bytes_to_write and bytes_to_read both being 0.
In this case the function always sets the write bit:
else if (master_bytesToWrite == 0 && master_bytesToRead == 0) {
twi_mode = TWI_MODE_MASTER_TRANSMIT;
uint8_t writeAddress = ADD_WRITE_BIT(master_slaveAddress);
TWI0.MADDR = writeAddress;
}
Am I missing something here? Or did somebody want to save a few lines, not having this special case in mind?
|
else if (master_bytesToWrite == 0 && master_bytesToRead == 0) { |
Today I ran into an issue while implementing a PMBus interface on an Arduino every.
PMBus derrives from SMBus which uses I2C and ultimately TWI.
From System Management Bus Specification Version 3.3:
This requires a 0 byte read or write transaction where the read is currently not possible with this implementation as the write bit is implicitly set in both cases.
Both cases result in a call to
with bytes_to_write and bytes_to_read both being 0.
In this case the function always sets the write bit:
Am I missing something here? Or did somebody want to save a few lines, not having this special case in mind?
ArduinoCore-megaavr/libraries/Wire/src/utility/twi.c
Line 322 in 5e639ee