UART Max Speed

Lorenz Gruebler

Hello TI-Engineers,

For availability reasons I plan to run two TMS570 MCUs in dual active mode. Therefore i want to connect then by a UART Line (UART Signals are transported by LDVS Transceivers). In the MCU Manual I found that the maximum Baud Rate ist 3125 kBit/sec.

Q: Is there a way to speed up the UART?

Q: Is the max. UART Baud Rate also reachable with lower CPU frequency?

Q: Is there any other common method for a fast serial connection of two TMS570?

regards

Lorenz

over 14 years ago

0 Tony Morrell over 14 years ago

Genius 4130 points

Hi Lorenz,

We're using the 20MHz rated SPI on our project to link a number of TMS570.

Regards, Tony.

0 Lorenz Gruebler over 14 years ago in reply to Tony Morrell

Expert 1075 points

Hi Tony,

I used that way also with other designs (two SPIs crossed over)

this is also my 2nd thought, but my CPUs are not located on the same PCB so I think with UART I can reduce the amount of connection wires (distance of the boards is up to 3 meters).

Maybe I switch to SPI

thank you

Lorenz

0 Tony Morrell over 14 years ago in reply to Lorenz Gruebler

Genius 4130 points

CAN would provide a robust link over the distance you require, but I guess from your UART speed questions, that the maximum 1MBaud is not fast enough.

0 Lorenz Gruebler over 14 years ago in reply to Tony Morrell

Expert 1075 points

CAN is too slow and has a lot of overhead,

so I think also the price of the components will decide.

thanks,

Lorenz

0 Sunil Oak over 14 years ago

TI__Mastermind 49120 points

Hi Lorenz,

The max baud rate achievable with the LIN/SCI module configured in SCI mode is 3.125M bits/second. The formula for calculating the asynchronous mode baud rate in the reference manual is incorrect - it is missing the factor 16 in the denominator. The SCI baud rate is calculated as (VCLK frequency) / [ 16 * (1 + P + M/16) ].

This will be corrected in the next update to the TRM.

Given this formula for deriving the SCI baud rate, the 3.125 Mbps is only achievable with a VCLK frequency of 100MHz.

Regards,

Sunil

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UART Max Speed