need help with oled and NRF52 DK

RE: need help with oled and NRF52 DK

vohra alihussain — Fri, 05 Oct 2018 13:52:41 GMT

hey do u get your answer?

i am also facing same type of problem

RE: need help with oled and NRF52 DK

Jørgen Holmefjord — Thu, 11 May 2017 17:34:14 GMT

An alternative if splitting the data does not work, is to use legacy TWI without EasyDMA. This can be selected by setting TWIx_USE_EASY_DMA 0 in sdk_config.h. Unfortunately the TWI master driver and HAL does not seem to have support for length parameters of more than 8 bits. You will have to change the driver/HAL implementations to support 16-bit lengths, or use the registers directly. I will check if I can make an example for you, but something like this code should work to do a TWI transfer using the registers:

uint32_t byte_number = 0;
NRF_TWI0->ENABLE = (TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos);
NRF_TWI0->PSELSCL = 27;
NRF_TWI0->PSELSDA = 26;
NRF_TWI0->FREQUENCY = TWI_FREQUENCY_FREQUENCY_K100;
NRF_TWI0->INTENCLR = 0xFFFFFFFFUL; //Disable all interrupts
NRF_TWI0->SHORTS = 0x00000000;
NRF_TWI0->ADDRESS = 0x3C;
NRF_TWI0->EVENTS_TXDSENT = 0;

NRF_TWI0->TXD            = 0x40; //control byte
NRF_TWI0->TASKS_STARTTX  = 1;


while (byte_number < sizeof(buffer)) {
	// wait for the transaction complete
	
	while (NRF_TWI0->EVENTS_TXDSENT == 0);

	NRF_TWI0->TXD            = buffer[byte_number];
	NRF_TWI0->EVENTS_TXDSENT = 0;
	byte_number++;
}

while (NRF_TWI0->EVENTS_TXDSENT == 0); //Wait for last byte

NRF_TWI0->EVENTS_STOPPED   = 0;
NRF_TWI0->TASKS_STOP       = 1;

while (NRF_TWI0->EVENTS_STOPPED == 0);

RE: need help with oled and NRF52 DK

phob — Tue, 09 May 2017 15:53:16 GMT

Thanks for correcting. Link is broken. Please share the link again. i have updated code in github. still not working.

RE: need help with oled and NRF52 DK

kian79 — Tue, 09 May 2017 04:38:02 GMT

Hi Jorgen,

There seems to be an issue with a repeated start bit between non stop transfers as discussed in this thread:

devzone.nordicsemi.com/questi...

I think splitting the buffer into multiple transfers of 255 bytes will not work too. Did you manage to find another solution?

RE: need help with oled and NRF52 DK

Jørgen Holmefjord — Thu, 27 Apr 2017 10:52:33 GMT

I see one more issue in the code. In function ssd1306_display(), the buffer is sent to the display in a single transfer. From the API documentation of nrf_drv_twi_tx(), you can see that the input length is of type uint8_t, meaning the maximum length of the transfer can be 255 bytes. This is due to the limited EasyDMA buffer in the nRF52 series. You have to split the buffer into multiple transfers of 255 bytes or less. With a resolution of 128x64 pixels, the transfer size will be 128*64/8=1024 bytes. When giving this number to the 8-bit length parameter, the variable will overflow and a lengt of 0 will be used, leading to no data being transferred. This thread might be of help.

RE: need help with oled and NRF52 DK

phob — Wed, 26 Apr 2017 17:49:09 GMT

Ok. I don't think there is any Initialization failed, because i compare 3-4 kinda code of different controller for the same oled. Init sequence is exact replica. I think there might be issue with i2c communication. Or May be because of blocking or non-blocking issue. I don't have working LA now.

RE: need help with oled and NRF52 DK

Jørgen Holmefjord — Mon, 24 Apr 2017 08:01:02 GMT

Yes, I get the same dots. Most likely there is something wrong with the initialization commands or the functions for writing to the OLED.

RE: need help with oled and NRF52 DK

phob — Fri, 21 Apr 2017 19:00:55 GMT

Thanks jorgen. I tried 0x3C address and partially oled works means backlight and some dots are coming. But it stucks at dots only. I am calling function to draw some bitmaps as well but no effect. obrazki.elektroda.pl/2093360400_1492801072.jpg is it same result you got or you got text on oled?

RE: need help with oled and NRF52 DK

Jørgen Holmefjord — Fri, 21 Apr 2017 08:38:06 GMT

The code from your GitHub is working with my display if I change the I2C address from 3D to 3C. Are you sure the OLED is powered correctly?

RE: need help with oled and NRF52 DK

phob — Thu, 20 Apr 2017 17:53:02 GMT

No, I think my code is not working at all. Even if i do LED ON then also no effect. I saw once LED backlight was ON, but later no such effect. I have updated code on github and link shared in 1st post.

RE: need help with oled and NRF52 DK

Jørgen Holmefjord — Tue, 18 Apr 2017 06:58:16 GMT

Yes, the backlight is enables in initialization (at least on my device). Do you get any error codes from the calls to nrf_drv_twi_tx? Have you checked that you are using the correct address for the device? You can scan for TWI devices using the TWI scanner example.

RE: need help with oled and NRF52 DK

phob — Thu, 13 Apr 2017 15:09:13 GMT

I checked with blocking mode, but it didn't work for me. Do i have to change jumper anywhere? I checked voltage and its proper, but like other lcd's which glow backlight, but with oled backlight is not coming. Do we have any example to refer?

RE: need help with oled and NRF52 DK

Jørgen Holmefjord — Tue, 11 Apr 2017 10:46:21 GMT

Hi,

The problem seems to be that you are using the TWI driver in non-blocking mode, but you do not have any mechanism implemented to make sure that the previous transfer is done before starting a new transfer. If you check the return code of your calls to nrf_drv_twi_tx() in ssd1306_command(), you will see that you get a lot of error code 0x11 - NRF_ERROR_BUSY. This leads to that the commands is not sent to the OLED.

A simple fix to this problem is to switch to blocking mode for the TWI instance. This is done by passing NULL to event_handler argument of nrf_drv_twi_init().

Best regards,

Jørgen