DM365 UART1 BAUD RATE

Max Chou14536

Prodigy 140 points

Dear All

I write a test appliation to verify UART1 driver,

and I use "cfsetispeed(&options, B19200); cfsetospeed(&options, B19200);" to set uart1 baud rate,

but when I use scope to measure the frequency of uart1, the speed is 96000 Hz,

it seems clock soure of uart1 is 121Mhz(PLL1->PLLDIV4), not 24Mhz(fixedrate)

does any one know this issue??

and how to correct it??

Sincerely,Max Chou

over 16 years ago

0 Mike Johnson over 16 years ago

Prodigy 30 points

See the HW errata document for the 365 - The UART baud rate divisor is bad, it is initially ~ 141 Kbaud on boot.

0 JerryJohns over 16 years ago in reply to Mike Johnson

Intellectual 650 points

No, this has nothing to do with that errata document - that item pertains to UART0 and its divider settings.

UART1 module gets a 120Mhz clock, and this is not properly documented in the datasheets. You can change that at the kernel level by modifying arch/arm/mach-davinci/board-dm365-evm.c and change the uart clock settings in that file.

Jerry

0 Mike Johnson over 16 years ago in reply to JerryJohns

Prodigy 30 points

My mistake ! Thanks for the clarification!

Mike

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DM365 UART1 BAUD RATE