What's the maximum of baud rate supported of UART?

Question

Hi, I have been trying to maximize the baud rate of my uart module, I am using the app_uart layer to control the uart and I have noticed that in your implementation of HCI you have set the baud rate to be 38400, and it is with hardware flow control. So I am guessing that's pretty much the max baud rate you can get without affecting the performance and robustness of the UART and without flow control the expected baud rate should be lower? Since mine UART constantly run into OVERRUN error so I am guessing the baud rate I set is too high?

ovrebekk · Accepted Answer

As Nils mentions the UART hardware can go up to 1 Mbaud, but if you use the BLE SoftDevice without any flow control this could lead to lost bytes from the UART peer to the nRF51822. 
 When the S110 SoftDevice is running, and is in a connected state, you could have interrupts from the stack in the 1-5ms range depending on the amount of data being exchanged (as of version 5.1.0. of the S110). This means that you need a very low baudrate to be 100% sure that you won't drop any bytes (for comparison 1 byte at 9600 baud takes about 1ms to transmit). 
 I think you have to do one of the following to get around this limitation: 
 
 
 Use flow control (preferred) 
 
 
 Use a low baudrate, 9600 baud or less 
 
 
 Have the nRF51822 inform the peer when it is ready to receive data, to avoid the peer sending data when the nRF51822 is interrupted.
Using the radio_notification feature it is possible for the nRF51822 to know when an interrupt from the S110 stack is about to occur.

What's the maximum of baud rate supported of UART?

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