AM335x PRU UART 10Mbps throughput

shammi kaplesh

Expert 1475 points

Other Parts Discussed in Thread: PROFIBUS

Hi,

We want to achieve throughput of 10mbps on UART(RS422) using PRU of am35x. It is possible to achieve that through PRU ?

Which UART port can be accessed from PRU unit ?

How can be communicate between am335x and PRU unit ?

Regards,

SHAMMI

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

Are you asking about the PRU hardware UART? See section 4.4.4 from the AM335x TRM Rev. N for information.

0 shammi kaplesh over 9 years ago in reply to Biser Gatchev-XID

Expert 1475 points

Hi,
Yes i am asking about PRU UART. Is it possible to achieve throughput of 10mbps ?
DO PRU has separate UART or it is using out of 6 UART vailable on am335x ?

Regards,
SHAMMI

0 Biser Gatchev-XID over 9 years ago in reply to shammi kaplesh

TI__Guru**** 393215 points

Please read the TRM section given above. You will find the answers there.

0 shammi kaplesh over 9 years ago in reply to Biser Gatchev-XID

Expert 1475 points

HI,

I gone through data sheet and i can see that max baud rate is 3000000. But one of our client requirement is 10mbps throughput. Can you please tell me whether we can achieve throughput of 10mbps using PRU hardware ?

Regards,
SHAMMI

0 Biser Gatchev-XID over 9 years ago in reply to shammi kaplesh

TI__Guru**** 393215 points

You can see the formulas for calculation the divisor on page 237:

Divisor = UART input clock frequency / (Desired baud rate * 16) (when MDR.OSM_ SEL=0)
Divisor = UART input clock frequency / (Desired baud rate * 13) (when MDR.OSM_ SEL=1)

UART input clock frequency is 192MHz. So you will get:

192 000 000 / (10 000 000 *16) = 1.2 (when MDR.OSM_ SEL=0)
192 000 000 / (10 000 000 *13) = 1.4769 (when MDR.OSM_ SEL=1)

You can see that there is no integer divisor that will get you exactly 10Mbps. With the closest integer divisor = 1 you will get either 12Mbps or 14.769Mbps.

0 shammi kaplesh over 9 years ago in reply to Biser Gatchev-XID

Expert 1475 points

Thanks, Can be access am335x uart0-5 from PRU hardware ?

Regards,

SHAMMI

0 Biser Gatchev-XID over 9 years ago in reply to shammi kaplesh

TI__Guru**** 393215 points

Yes, the PRU can access the external memory space, however UART[5:0] maximum baud rate is even lower than the PRU UART, as they are clocked at 48MHz.

0 Adavala Sudheer over 9 years ago in reply to Biser Gatchev-XID

Intellectual 340 points

Hi Biser,

I have to Exercise the PRU-UART with baud rate of 12Mbps, I understood as per TRM it is possible to achieve the desired baudrate by changing DLL and DLH. AM335x EVM support this..? If its supports on which serial port connector and what is the #profile selection ?

I have found the UART pins on EVM schematic (PR1_UART0_RXD(B16) ,PR1_UART0_TXD(A16)) these pins can I use ?.

Thanks & Regards,

Sudheer A.

0 Biser Gatchev-XID over 9 years ago in reply to Adavala Sudheer

TI__Guru**** 393215 points

Please read the thread before posting. 12Mbps is not possible to achieve on AM335x.

Edit: I mean on the standard UARTs.

0 Frank Walzer over 9 years ago in reply to Biser Gatchev-XID

TI__Mastermind 44306 points

Biser,

why do you say this? PRU UART is required to run at 12Mbps for PROFIBUS.

Regards,

0 Adavala Sudheer over 9 years ago in reply to Adavala Sudheer

Intellectual 340 points

Hi Biser,

My requirement is to test upto 10Mbps.

Regrds,
Sudheer A.

0 Adavala Sudheer over 9 years ago in reply to Frank Walzer

Intellectual 340 points

Dear Biser,

My requirement is to test PRU-UART upto 10Mbps, as per the TRM it should support upto 12Mbps.
Its ok my question is on EVM can I exercise this..?

Regards,
Sudheer A.

0 Biser Gatchev-XID over 9 years ago in reply to Adavala Sudheer

TI__Guru**** 393215 points

The PRU UART functionality is not available on the AM335x GP EVM.

0 Adavala Sudheer over 9 years ago in reply to Biser Gatchev-XID

Intellectual 340 points

Dear Biser,

Thanks for information. Can I test this in BeagleBoneBlack board..? If its supports could you pls share some example to exercise the PRU UART.

Thanks & Regards,
Sudheer A.

0 Biser Gatchev-XID over 9 years ago in reply to Adavala Sudheer

TI__Guru**** 393215 points

Yes, on BBB these are the following processor pins:

D15: UART1_TXD/MMC2_SDWP/DCAN1_RX/I2C1_SCL//PR1_UART0_TXD/PR1_PRU0_PRU_R31_16/GPIO0_15

D16: UART1_RXD/MMC1_SDWP/DCAN1_TX/I2C1_SDA//PR1_UART0_RXD/PR1_PRU1_PRU_R31_16/GPIO0_14

D18: UART1_CTSN/TIMER6/DCAN0_TX/I2C2_SDA/SPI1_CS0/PR1_UART0_CTS_N/PR1_EDC_LATCH0_IN/GPIO0_12

D17: UART1_RTSN/TIMER5/DCAN0_RX/I2C2_SCL/SPI1_CS1/PR1_UART0_RTS_N/PR1_EDC_LATCH1_IN/GPIO0_13

Which come out on the expansion headers with 3.3V signal levels. However I'm not aware of any software examples available. You will have to write your own code to do this.

0 Adavala Sudheer over 9 years ago in reply to Biser Gatchev-XID

Intellectual 340 points

Dear Biser,

Thanks for providing the information.

Thanks & Regards,
Sudheer A.

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AM335x PRU UART 10Mbps throughput