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

[RodWatt]

Hi Sigurd,

OK, I have carried out some more testing but still not connecting. I have a BMP280 I2C device plugged in and working so I am confident that my pin assignment and I2C interface is working OK.

I have tried two different grove LCDs, 

http://wiki.seeedstudio.com/Grove-16x2_LCD_Series/

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

both using this code

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

my overlay file looks like this

&i2c2 {
        status = "ok";
        sda-pin = <30>;
        scl-pin = <31>;
        clock-frequency = <I2C_BITRATE_STANDARD>;
        grove_display@3e {
		compatible = "grove, grove_display";
		reg = <0x3e>;
		label = "GROVE LCD";
	};
};

but I get the same error for both

Secure Boot: MSP_NS 20021620

Secure Boot: prepare to jump to Non-Secure image

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

Grove LCD: Device not found.

Really appreciate any pointers here, Im starting to go crazy!

Thanks,

Rod

[Jan Tore Guggedal]

Hi Rod, 

After a quick look at the Grove LCD driver it looks like it doesn't obtain I2C device information from the device tree like it should, but rather from Kconfig. Could you try to set 

CONFIG_GROVE_LCD_RGB_I2C_MASTER_DEV_NAME="I2C_2"

in your prj.conf and see if that helps. 

Best regards  

Jan Tore 

[RodWatt]

Hi Jan, 

Thats it!! Excellent, thank you 

Rod