simon_cielo Posted November 11, 2012 Report Share Posted November 11, 2012 Does windows xp support the 691200 or 921600 baud rate?How can I check the current baud rate of the com port?Thanks! Quote Link to comment Share on other sites More sharing options...
Gandalph Posted November 11, 2012 Report Share Posted November 11, 2012 Baudrates in a PC are controlled by a UART and a crystal. The crystal frequency determines what baudrates the serial port can generate. The baudrate is often generated by a divide by 16 counter. The crystal frequency for a standard PC is normally 1.8432 MHz. Dividing that by 16 gives you 115200 which is usually the maximum the com port can do.Inside the UART is a DLAB register. This further divides the clock. So essentially, to get 5787 baud you're talking about dividing 115200 by 5787 which gives you 19.906687... It's close to 20 you'd load the DLAB register with 20. 115200 / 20 gives you 5760. Therefore you're probably getting 5760 baud out of the PC com port. That's probably enough of a difference to cause the issue that you're seeing. Quote Link to comment Share on other sites More sharing options...
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