AM3352: Changing console from UART0 to UART1

Miyazaki-san,

Takayuki Miyazaki said:

Changing the default debug console on the AM335x from UART0 to UART1.

There's a description (including a PATCH) showing you exactly where you need to make modifications to change the console UART in both U-Boot and Linux on AM335x in this E2E post here: https://e2e.ti.com/support/processors/f/791/p/905798/3349581#3349581

This topic is also discussed in the "Customize console UART settings" section in our AM335x U-Boot board-port guide located here: https://software-dl.ti.com/processor-sdk-linux/esd/docs/06_03_00_106/AM335X/linux/How_to_Guides/Board_Port/U-Boot.html

Takayuki Miyazaki said:

Customer is trying to communicate UART1 using the J10 connector on daughter board with AM335xGP-EVM

Some things to double-check:

• UART1 will need to be set to status = "okay" in the DTS to enable it
• Make sure the pinmux matches the board/connections (should already be in case of using the original AM335x EVM with am335x-evm.dts)
• Try outputting something directly to the UART device in Linux by doing echo Test > /dev/ttyS1

Regards, Andreas

Hello Andreas,

Thank you for your helpful comments.  I'd like to wait customer's feedback for a while.

best regards,

Miyazaki

Hello Andreas,

Regarding UART1 communication, I received customer's feedback. customer was not able to resolve this issue yet. Customer confirmed them as follows.

>1. UART1 will need to be set to status = "okay" in the DTS to enable it

Customer confirmed status = "okay" for UART1 in am335x-evm.dts

>2. Make sure the pinmux matches the board/connections (should already be in case of using the original AM335x EVM with am335x-evm.dts)

Customer believes there is not any issue for this.

uart1_pins: pinmux_uart1_pins {

pinctrl-single,pins = <

   AM33XX_IOPAD(0x978, PIN_INPUT | MUX_MODE0)

   AM33XX_IOPAD(0x97C, PIN_OUTPUT_PULLDOWN | MUX_MODE0)

   AM33XX_IOPAD(0x980, PIN_INPUT_PULLUP | MUX_MODE0)

   AM33XX_IOPAD(0x984, PIN_OUTPUT_PULLDOWN | MUX_MODE0)

>;

};

After that, customer did " echo Test > /dev/ttyS1", it still failed. Is there any other check-points for this?

Although I tried to check daughter-board schematic, I was able to check it because of Orcad file.  it will be appreciated if you will share your advice again. 

Best regards,

Miyazaki

Miyazaki-san,

Takayuki Miyazaki said:

After that, customer did " echo Test > /dev/ttyS1", it still failed. Is there any other check-points for this?

Where did the customer try to connect to the UART1 signals (AM335X_UART1_TXD @ ball D15, AM335X_UART1_RXD @ ball D16)? Reviewing the documentation at https://processors.wiki.ti.com/index.php/AM335x_General_Purpose_EVM_HW_User_Guide there does not seem to be a way to readily access those signals without making modifications to a board despite it may seem like one can easily route those signals to one of the other DB9 connectors. This E2E post here confirms that: https://e2e.ti.com/support/processors/f/791/t/550858?AM335x-GP-EVM-profile-for-UART1

What you could do is the following:

1. Install R225, R229, R232, and R236 on the CPU board. Remove R354, R355, R356, and R357. Then access the (logic-level) UART signals directly through the expansion connector J5. Then, they should also be available on the daughter board connector J10 as per schematic (more below).
2. Access the UART signals (logic level, and shifted to 1.8V) through the COM connector (J11)

Also, your DTS file looks good, assuming a connection via device balls D15 and D16.

Takayuki Miyazaki said:

Although I tried to check daughter-board schematic, I was able to check it because of Orcad file.  it will be appreciated if you will share your advice again.

Attached a PDF version of the AM335x GP Daughterboard schematic. I've also submitted an internal request (ref: SUBARCTICAPPS-169) to have that PDF document added to the official AM335x GP Daughteboard schematic package (TI lit # sprr165).

Regards, Andreas

am335x_gpevm_gpdboard_3h0001_schematic_rev1_2b.pdf

Hello Andreas,

I got feedback from customer at this time. It seems customer has still issue. I mean, customer was not able to confirm UART1 signals on daughter board connector J10. Customer was able to confirm UART1 signals on daughter board connector J3. But, there is U43C(Altera EPM2210F324) between J3 and J10. It does not seem that this cPLD passes through UART1 signals. Could you elaborate how customer is able to configure, please?

Bes regards,

Miyazaki

Miyazaki-san,

Takayuki Miyazaki said:

Customer was able to confirm UART1 signals on daughter board connector J3.

Does this mean the customer can receive/send (logic-level) UART data through J3?

Takayuki Miyazaki said:

But, there is U43C(Altera EPM2210F324) between J3 and J10. It does not seem that this cPLD passes through UART1 signals.

If I remember correctly the schematic I had looked at did not have the FPGA in the signal path.

What specific board revision is the customer using? It should be printed on the base board and the daughter board. With knowing the specific version I'd be able to have another close look.

Regards, Andreas

Hi Andreas,

Yes, Customer was able to confirm UART1 signals on J3 connector (daughter board) after resisters modification, as you had advised. According to “am335x_gpevm_gpdboard_3h0001_schematic_rev1_2b.pdf” which you shared with us previously( on above thread), I noticed there is FPGA on this board. This means, I believe that the revision of daughter board is v1.2b. as far as I tried to check this schematic, I don’t believe there is any configuration pins of FPGA. 

Best regards,

Miyazaki

Hi Andreas,

Thank you for your clarification.

Although I also have tried to looked for profile setting (DIP Switch SW8) of cPLD on daughterboard, I was not able to find the detail information. But, I found vhdl source code for cPLD (https://processors.wiki.ti.com/index.php/AM335x_General_Purpose_EVM_CPLD). According to this source code, I noticed AM335X_UART1 signals were not connected to UART1 signals, regardless of configuration-pins(Profile setting) . Therefore, I will suggest customer to use some blue wires to get the UART1 signals to U15(MAX3232E) if possible. I believe it is easy way.  I'd like to wait for customer's feedback for a while.

Best regards,

Miyazaki

Hello Andreas-san,

Customer understood  this. Thank you for your advice.

Best regards,

Miyazaki