Hello Guys , 

 

I have ordered Micro SD Card Breakout for Exporting UART and JTAG Pins to get serial output on the SD card port without making any welding on the box.

I have test it and it seems to work. The problem is that the output is some king of unreadable characters.

 

I don't know whether it is a config issue or something else ?

 

Does any one have used the UART over SD port ?

 

Thanks,

Euuhh ??? SD Card slot doesn't have any UART and JTAG pins, it is either SPI or SDIO ...

Do you mean a breakout board that is using some SPI to UART bridge such SC16IS760 chip ?

In this case, your need to make sure that your kernel has this chip kernel driver built-in.

I've no idea about JTAG ...

 

Depends on what SoC your tv box has and which pins the SD slot connect to.

Eg: If it were an old A20 chip, the SDC0 pins on port PF are shared with UART0 and JTAG

To switch the functionality of these pins you need the correct FEX/DeviceTree settings.

6 hours ago, martinayotte said:

Euuhh ??? SD Card slot doesn't have any UART and JTAG pins, it is either SPI or SDIO ...

Example: https://linux-sunxi.org/MicroSD_Breakout

That is the model that I was referring to: https://linux-sunxi.org/MicroSD_Breakout

 

I have bought something similar and it does send uart data over SD(It is the case for all amlogic socs.), the only problem is that this data is unreadable (unreadable chars). knowing that I'am using the S905X soc.

6 hours ago, zador.blood.stained said:

Example: https://linux-sunxi.org/MicroSD_Breakout

Oh ! I missed that ! Sorry ...

The one I was talking about was one developped by Pinebook user Machinum : https://forum.pine64.org/showthread.php?tid=5055&pid=31807#pid31807

 

Well it was a connector issue, I have changed connector and it worked like a charm, I have tested the device connector on S905, S905X and S905W with a success.

 

This is good news because we don't need anymore to weld any thing on the board to get a serial output, we could even setenv on u-boot without booting on android or even root it.

 

For those who are interested here is the link from where I have ordered the devices:

Micro-SD-Card-Breakout-for-Exporting-UART-and-JTAG

 

Have a nice uarting

1 hour ago, rafaelSorel said:

I have tested the device connector on S905, S905X and S905W with a success.

I assume you had to use different pins for the S905, it appears they have TX on the D3 pin and RX on D2

A20's have RX and TX on D3 and CLK.

 

You'd need to update uboot to use the different uart though, wouldn't you?

No update at all, I have used the device as shipped, (no changes were made to dtb files) .

On 1/31/2018 at 2:32 PM, rafaelSorel said:

Well it was a connector issue, I have changed connector and it worked like a charm, I have tested the device connector on S905, S905X and S905W with a success.

 

This is good news because we don't need anymore to weld any thing on the board to get a serial output, we could even setenv on u-boot without booting on android or even root it.

 

For those who are interested here is the link from where I have ordered the devices:

Micro-SD-Card-Breakout-for-Exporting-UART-and-JTAG

 

Have a nice uarting

Can you explain what you mean by connector? or post the instructions to make the connections between serial adapter and Micro SD Card Breakout?