Serial Console for the Rock64

[ClaudiaF]

Hello,

I'm wondering if I can reuse my arduino uno r3 as the adapter.
Disabling the microchip by connecting RESET with GND
and connect 
arduino pin0 (rx) to rock64 pin10(rx)
arduino pin1 (tx) to rock64 pin8(tx)
arduino pin14 (gnd) to rock64 pin6(gnd)

I'm not sure if it is necessary to disable the avr chip on the uno r3 or if it can be on
and use the builtin serial monitor of the arduino ide.

What do you think?

Cheers
Claudia

[tllim]

Hello,

I'm wondering if I can reuse my arduino uno r3 as the adapter.
Disabling the microchip by connecting RESET with GND
and connect 
arduino pin0 (rx) to rock64 pin10(rx)
arduino pin1 (tx) to rock64 pin8(tx)
arduino pin14 (gnd) to rock64 pin6(gnd)

I'm not sure if it is necessary to disable the avr chip on the uno r3 or if it can be on
and use the builtin serial monitor of the arduino ide.

What do you think?

Cheers
Claudia

The ROCK64 UART required 1.5Mb speed, not sure whether your Arduino Uno UART chip able to operate under such speed.

[ClaudiaF]

The ROCK64 UART required 1.5Mb speed, not sure whether your Arduino Uno UART chip  able to operate under such speed.

Hello tllim,

thank you for your answer, very much appreciated.

The arduino IDE specifies a maximum of 2Mb baud and if I set this value and within code initializing
serial.begin(1500000), I do get results showing in the builtin monitor console.

I already found out, that I have to disable the avr chip in order to make this work but my biggest concern
is the different voltage. If I measure arduino tx/rx pins I do see 5V and on rock64 only 3.3V.


On different sites it is mentioned that it MAY work but I can't find one which states that it was tested
and it works.

I'm unsure if it is enough to put an resistor between arduino tx / rock64 tx and arduino rx / rock64 rx.

Cheers
Claudia

[MarkHaysHarris777]

The ROCK64 UART required 1.5Mb speed, not sure whether your Arduino Uno UART chip  able to operate under such speed.

Hello tllim,

thank you for your answer, very much appreciated.

The arduino IDE specifies a maximum of 2Mb baud and if I set this value and within code initializing
serial.begin(1500000), I do get results showing in the builtin monitor console.

I already found out, that I have to disable the avr chip in order to make this work but my biggest concern
is the different voltage. If I measure arduino tx/rx pins I do see 5V and on rock64 only 3.3V.


On different sites it is mentioned that it MAY work but I can't find one which states that it was tested
and it works.

I'm unsure if it is enough to put an resistor between arduino tx / rock64 tx and arduino rx / rock64 rx.

Cheers
Claudia

Theoretically a 1K resistor in-line will work;  but don't do it.  

Always use a level shifter;  there are several good ones on the market ( very tiny ) from places like Sparkfun ;  or you can make your own with an  LM319 open collector comparator.   

words of warning:  never touch 5v to any gpio pin of the PineA64+ or the Rock64 , nor the Padi Stamp... or you'll get magic blue smoke and the board(s) will be toast.

[ClaudiaF]

Theoretically a 1K resistor in-line will work;  but don't do it.  

Always use a level shifter;  there are several good ones on the market ( very tiny ) from places like Sparkfun ;  or you can make your own with an  LM319 open collector comparator.   

words of warning:  never touch 5v to any gpio pin of the PineA64+ or the Rock64 , nor the Padi Stamp... or you'll get magic blue smoke and the board(s) will be toast.

Hello marcushh777,

thank you very much for your thoughts.
I'm a newbie when it comes to hardware and electronics and I'm thankful that you provided different solution to the issue.
I guess I go with the level shifter, as far as I remember a friend of mine mentioned something like this - so maybe I can borow it.

Cheers
Claudia

[inos]

I would like to use an old Raspberry Pi 1B (with a PiFace digital card) to monitor my Rock64 board. Therefore I'm using the serial to USB adaptor (shipped from pine64) to connect the Rock64 to the USB2 port of the RPi1.
Unfortunately the USB2 port of the RPi1 seems to be too slow to handle the 1.5M baud rate delivered by the Rock64 as I have some data skipped/ dropped.
Is there a simple way to reduce the baud rate or do you have any other idea how to handle this?
I would like to use this combination of hardware because (I have it already at home) despite of monitoring via UART, with the PiFace board I can remotely reset and/or power off devices...

Thanks for your help!
Cheers Martin

[xalius]

Why do you not just connect the UART of your RPI to the UART of the Rock64 directly? If you still want to usb USB/serial adapters, you need one that supports the baudrate of 1.5Mbit like PL2303HX, FT232RL....

[inos]

Why do you not just connect the UART of your RPI to the UART of the Rock64 directly? If you still want to usb USB/serial adapters, you need one that supports the baudrate of 1.5Mbit like PL2303HX, FT232RL....

Thank you for your reply.
The USB adapter does support the baudrate - I have no problem with this when being connected to my notebook. But as far as I have understood all the posts I found, the RPi UART supports up to 1Mbps only  (http://fw.hardijzer.nl/?p=138)
In theory, the USB 2.0 specification is designed for up to 480 Mbps/60MBps so the bottleneck might be the CPU itself? I'm using picocom (https://github.com/npat-efault/picocom) as terminal program...

[xalius]

I usually use minicom on the boards and my laptop/PC that works fine and most distros have that as a package, I don't think it's a bandwidth problem on the RPi with the USB dongle...

[inos]

Thanks for the advise! I have played around with picocom, minicom, tio and kemit without success.
If I e.g list a directory, I can see a line for some milliseconds but this one is erased or overwritten.
I have also tried to go via a ssh connection to eliminate slow graphics/ framebuffer but with the same result.
Even with full overclocking/turbo mode, the RPi 1 seems to be too slow (RAM maybe?) for a baudrate of 1.5M

Does anyone know a way to reduce the standard baudrate to 128k?

Thank you for the help!

Martin