Are Raspberry PI hats/displays compatible with the rock64?


joey99
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The GPIO pins on the Rock64 are very similar to the Raspberry Pi's GPIO, except the Raspberry pi calls pin #19 GPIO 10, pin #21 GPIO 9 and pin #23 GPIO 11. Where as the Rock64's pin #19 is GPIO3_A1, pin #21 GPIO_A2 and pin #23 GPIO3_A0. The Rock64 documentation does say that it is quasi-Raspberry Pi compatible, but it's hard to find anyone who has actually tested this.

 

Here is the GPIO layout of the Rock64, compared to the Pi 3

rock64-gpio-header.jpg&f=1&nofb=11*A2gpUDLyOx903dVUStHFTA.jpeg&f=1&nofb=1

 

 

I'm currently trying to figure out if a display such as THIS can be connected to the Rock64's GPIO pins without any major issues. User documentation for the display can be found HERE on page 2, in the PDF named 5inch_HDMI_Display_User_Manual.

 

Any information will be greatly appreciated.

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Hello @joey99,

 

   This is a bit of a complicated question, I'll give it my best shot.

 

The Raspberry Pi GPIO's are tied to the Broadcom SoC and as such are named accordingly.  This will not be the numbering found on any other board with an open market SoC.  So the numbers will never line up on anything else, since no one is allowed to buy the processors used by the RPi foundation.

 

To the GPIO on the RK3328 (The SoC found in the Rock64), Rockchip arranges it's GPIO thusly:

 

Bank ---> Group ---> Pin

 

The RK3328 has GPIO0,1,2,3

 

Each has a theoretical 32 pins, grouped A0-7, B0-7, C0-7, and D0-7

 

Linux will assign these a scalar value, IO 0- whatever the top number is.  That's where my knowledge ends.  In short, your hat should work, assuming you have the drivers for it and can extract the proper pin numbers out of the documentation.

 

[Edit] and on second look ,that display is HDMI, but I assume you were thinking of SPI LCD's.  A GPIO TFT LCD will not be compatible as the Rockchip pins for parallel LCD are not sent to the same places.

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Hello @TonyMac32, many thanks for the information!

 

I did some further research, and it looks like the TXD and RXD on the Rock64 is on pins 19 and 20. Where as on the Pi, it's on pins 8 and 10. So you are right, the display might not work on the rock64 if I were to use the SPI interface, rather than the HDMI. I don't want to risk damaging my Rock64, so I'll hold off on that display until I get a PI.

 

I did found a very detailed document HERE that goes over all of the pins on the Rock64. If an SD card is in place, pins 19, 21, 23 and 24 will become unavailable, as those occupied by the memory chip.

 

So long story short, I think I'll continue to use my monitor as a display for my Rock64. Which is strange, as other documentations did say that the Rock64 is quasi-Raspberry pi compatible, but oh well. The Rock64 is a great emulation machine for it's price, since I got the bundle on Amazon. It's just a shame that not a lot of GPIO devices support the Rock64.

 

EDIT: also found this very detailed post that goes over the rock64's GPIO pins. Forum link

 

Edited by joey99
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As Tony said. That display is HDMI. It only takes 5V from the GPIOs. The Rock64 has the same form factor. So even the HDMI adapter should work.
I use a simular 3.5" display on boards like the Odroid C2.
You can also power the display with micro-USB from the USB ports of your device if you don't want to put it on the GPIO's or if it doesn't fit.

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You can get the spi displays to work, but it's not going to be as easy as it is on a raspberry pi.

 

There are a bunch of old howtos for waveshare screens on orange pi boards and if you use a 4.x.y kernel they will still work but you will have to figure out the gpio numbers for the exact board you are using. 

 

If you want to use a kernel later than 5.17 or something you have to build a dtoverlay, which is a bit on the arcane side. 

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4 minutes ago, ej0rge said:

You can get the spi displays to work, but it's not going to be as easy as it is on a raspberry pi.

 

There are a bunch of old howtos for waveshare screens on orange pi boards and if you use a 4.x.y kernel they will still work but you will have to figure out the gpio numbers for the exact board you are using. 

 

If you want to use a kernel later than 5.17 or something you have to build a dtoverlay, which is a bit on the arcane side. 

 

Ya, I though it would not be as simple. Shame there isn't as big as a community for the rock64 compared to Raspberry or even the Orange pi, especially on emulation. It's a pretty solid board for that.

 

 

On 11/27/2020 at 4:44 PM, NicoD said:

As Tony said. That display is HDMI. It only takes 5V from the GPIOs. The Rock64 has the same form factor. So even the HDMI adapter should work.
I use a simular 3.5" display on boards like the Odroid C2.
You can also power the display with micro-USB from the USB ports of your device if you don't want to put it on the GPIO's or if it doesn't fit.

The issue is to connect the Rock64 to the display using the provided HDMI angle adapter, I'll have to connect it to the GPIO too. Which is still uncertain as the GPIO's on the Rock64 are slightly different than on the raspberry pi, as what Tony stated. Not sure if it would cause any damage to either the board, screen or both. I could also just use an HDMI cable, but I want to be able to mount the Rock64 on the back of the display with the provided display housing, while also using the provided HDMI angle adapter as it is much neater/cleaner looking.

 

Unless of course if I use the provided HDMI adapter while it is connected to the GPIO, the pins will be bypassed except the 5v and ground. Otherwise, I'll keep looking around for a display without a GPIO connector.

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17 minutes ago, joey99 said:

Ya, I though it would not be as simple. Shame there isn't as big as a community for the rock64 compared to Raspberry or even the Orange pi, especially on emulation. It's a pretty solid board for that.

 

 

The issue is to connect the Rock64 to the display using the provided HDMI angle adapter, I'll have to connect it to the GPIO too. Which is still uncertain as the GPIO's on the Rock64 are slightly different than on the raspberry pi, as what Tony stated. Not sure if it would cause any damage to either the board, screen or both. I could also just use an HDMI cable, but I want to be able to mount the Rock64 on the back of the display with the provided display housing, while also using the provided HDMI angle adapter as it is much neater/cleaner looking.

 

Unless of course if I use the provided HDMI adapter while it is connected to the GPIO, the pins will be bypassed except the 5v and ground. Otherwise, I'll keep looking around for a display without a GPIO connector.

 

That screen probably connects the touch panel through GPIO which is not near as big of a deal as getting the whole screen working through the gpio header.  If you don't want the touch function, you can ignore it. 

 

It looks like the only way to push video to that screen is hdmi. Which should be fine. 

 

As for whether the connectors will line up? The Rock64 has the same footprint as the raspberry pi 3 and the connectors appear to be in the same places? I'd rate it a solid "maybe". 

 

https://files.pine64.org/doc/rock64/rock64 board dimension.pdf

 

https://www.mouser.com/new/dfrobot/dfrobot-raspberry-pi-3-bplus/

 

 

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