nRF9160 driving the grove_display

[RodWatt]

Hi,

Has anyone tried connecting the grove_display to the nRF9160?

http://wiki.seeedstudio.com/Grove-LCD_RGB_Backlight/

I have tried the code below

https://github.com/zephyrproject-rtos/zephyr/tree/master/samples/display/grove_display

and created an overlay file

&i2c2 {
        status = "ok";
        sda-pin = <1>;
        scl-pin = <0>;
        clock-frequency = <I2C_BITRATE_FAST>;
        grove_display@0 {
		compatible = "grove, grove_display";
		reg = <0x0>;
		label = "GROVE LCD";
	};
};

and I get the error

Secure Boot: MSP_NS 20020580

Secure Boot: prepare to jump to Non-Secure image

***** Booting Zephyr OS v1.13.99-ncs1-5561-gde69d2df908f *****

Grove LCD: Device not found.

I guess there's an error in my overlay file?

Rod

[Jan Tore Guggedal]

Hi Rod,

It looks like the I2C address of your device is missing in the overlay file. It should be present like this:

...
        grove_display@address {
		    ...
	    	reg = <address>;
...

Hopefully that helps.

Best regards,

Jan Tore

[RodWatt]

Thanks Jan,

Ahh, missed that, cheers. Looking at the data sheet

http://www.newhavendisplay.com/specs/NHD-0220D3Z-FL-GBW-V3.pdf

this should be set to 0x50.

Unfortunately, Im still getting the same error. I note that the max I2C speed on the device is 50kb/s. (Page 6 of the datasheet)

In my overlay file, the clock speed is set to I2C_BITRATE_FAST. Looking at the include file, this defines a speed of 400kb/s

#define I2C_BITRATE_FAST 400000 /* 400 Kbit/s */

There isn't a definition for a speed of 50kb/s, the slowest speed is 

#define I2C_BITRATE_STANDARD 100000 /* 100 Kbit/s */

which doesn't work.

I have tried to define a slower speed

#define I2C_BITRATE_SLOW 50000 /* 50 Kbit/s */ but when I reference this is my overlay file, I get an error.

Please can you confirm which I2c.h file I should be updating? Am I missing anything else?

Rod

[Sigurd]

Hi,

Could you try e.g. pin 11 and 12 instead ? Looking at the DK user guide, it's possible that pin 0 and 1 is used for the UART. See this link.

If you still have issues after switching pins, try using i2c3 instead.

[RodWatt]

Hi Sigurd,

I can try this but I don't think this is the issue. I have tried outer I2C peripherals connected to pin 0 & 1 and these work fine. Did you see my comment above about the clock speed? I think the I2C clock is too fast? How can I define a clock speed of 50kb/s?

[Sigurd]

RodWatt said:

How can I define a clock speed of 50kb/s?

 You won't be able to set it to that. Min setting is 100 kbps, but the nRF9160 supports clock stretching, but it might not be enabled, check if the no_stop flag is set. See this link.

[RodWatt]

Hi Sigurd,

OK, I have moved the I2C pins to other pins and still getting the same error. I have confirmed that my other I2C device is still working so I don't think thats the problem.

How do I set the no_stop flag?

Rod