Recommended Touchscreen for nRF52810

[Jeremysee]

Hello,

I am designing a wearable using the nRF52810 chip and would like to ask if there are any recommended touchscreens to be used? My main concerns are

• SPI bus (at 8MHz) is fast enough to drive a suitable refresh rate
• Size, looking for something around a 1 inch diagonal/diameter
• Touch interface that is compatible with the chip

Thank you!

[Jeremysee]

The screen I'm looking at uses a dual SPI interface, to use it a 60Hz refresh rate requires a 45Mbps data rate.

[Jørgen Holmefjord]

If you want to use Dual SPI mode, you will have to move to nRF52840. This has a QSPI peripheral, supporting single/dual/quad line SPI.

[Jørgen Holmefjord]

240x240 @ 60 Hz corresponds to 3 456 000 bits/s. This should be possible with a dedicated SPI interface if it supports constantly streaming data, but you will have to verify this with your hardware. If you will be reading touch data through the same interface, you might be facing throughput issues.

[Jeremysee]

What would happen if I were to try and run it on the nRF52810? I am not intending to play animations on the screen, just update data once the touchscreen is pressed.

[Jørgen Holmefjord]

I'm not sure I understand your question. Do you have any specific doubts about getting it to work with nRF52810?

[Jeremysee]

Will the nRF52810 limited SPI bus speed bottleneck the screen refresh rate? If yes, is it possible to reduce the refresh rate or would it be more advisable to switch to the nRF52840?

[Jørgen Holmefjord]

Like I explained above, the 8 MHz SPI interface is capable of transferring more than double the data rate required for 240x240 pixels @ 60 Hz refresh rate. If the interface will be a bottleneck will depend on how data are written to the display, and how often you need to update the data being transmitted.

If you can reduce the refresh rate is not something I can answer. You will have to check the datasheet of your device about that. The nRF can control anything over SPI so if you display support lower refresh rates, there should be no problems.

[Jeremysee]

Thank you so much for the clarification! May I ask if there is any example code for writing an image to a display?

[Jørgen Holmefjord]

We have a GFX Library Example that can be used as a starting point.