Posts: 6
Joined: Tue Sep 25, 2018 2:11 pm
Location: Denver, CO, USA


Sun Oct 21, 2018 2:56 pm

I am in the final stages of schematic capture for a custom CM3 Carrier board. I need a CSI port on my carrier board. My question is about the CMIO schematic, there are two pins, #17 and #18 (on the 22-pin CSI connector) that are labeled CAM0_IO0 and CAM0_IO1, respectively. There is no connection to the Compute Module on the schematic for these pins. I have tested continuity on the CMIO board, and IO0 and IO1 do not seem connect to any pin on the Compute Module. I see in the dts blob for CM3 (the one from the official support site for using 1x display and 1x camera) that there are the following pins related to the camera: CAMERA_0_LED, CAMERA_0_SHUTDOWN, and CAMERA_0_UNICAM_PORT. I don't know what if any relation these pins have to each other, but I just want to make sure there is no relation, and I am hoping someone knows with confidence what to connect IO0 and IO1 to, or if I am supposed to leave them floating. In addition, what are the LED, Shutdown and Unicam_port pin defines?

Here is the context of the pins in the dts blob:

[email protected]_0_LED {
type = "internal";
number = <4>;
[email protected]_0_SHUTDOWN {
type = "internal";
number = <5>;
[email protected]_0_UNICAM_PORT {
type = "internal";
number = <1>;

Thanks for your help!

EDIT: I did some research on the V2.1 Raspberry Pi Camera, and it seems pin 17 is connected to the enable pin for the buck converters on the Pi cam board. Pin 18 is the clock out signal from the XTAL on the Pi Camera board. So I am assuming leaving pin 18 floating and connecting pin 17 to CM_VREF is correct? Can anyone else verify this?

Posts: 1480
Joined: Tue Jun 30, 2015 1:35 pm

Re: CMIO CSI IO pins

Mon Oct 22, 2018 4:52 am

1. Have you read the tutorial on how to connect a camera to CMIO?
2. Ever looked at a Raspberry Schematic (i.e, Zero or RPi3)

Now it should be clear how to connect those signals.

Keep in mind that camera0 (on a standard pi) is actually using CSI1 (unicam port 1; see below). That's because CSI1 is the 'more capable' peripheral as it exposes 4-lane DSI (on CMIO only, 2-lanes on standard Pi).

Code: Select all

[email protected]_0_UNICAM_PORT {
type = "internal";
number = <1>;  

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