RoboClaw Solo 300: issue with RS-485 control on S3
Posted: Wed Jul 07, 2021 2:56 pm
Using Motion Studio I have set the S3 output on my RoboClaw Solo 300 to RS-485 direction. This sort of works, with S3 going high just as the RoboClaw begins to transmit a response. However, at 460800 baud, it goes low again before all the data is sent, typically losing the last three bytes. On a simple command like #15 Read Serial Timeout, S3 is active just long enough for the first start bit of the response to get out -- about 3us. So with the transmit driver turned off for the rest of the byte, it is interpreted as 0xFF. The CRC bytes are not seen at all. (The unit has firmware version 4.1.35.)
This looks a lot like S3 is being turned off when the last byte goes into the UART transmit queue, instead of after it has been sent.
This looks a lot like S3 is being turned off when the last byte goes into the UART transmit queue, instead of after it has been sent.