nRF9160 with m4 MCU, camera, and LCD screen project

aldras · 2021-01-16T04:30:22+00:00

I am going to start a thread here and update it with the progress of a nRF9160 project that I am working on to get some feedback and also provide a starting...

aldras

By the way, I really do like this antenna, nice find!
Need to do some more testing but this flexible LTE antenna is really neat.

aldras

Next bump I ran into.
I wanted to power the nRF9160 from one of the header pins, I don’t want to push 3V3 through the 3V3 pin since I am not sure the Feather M0 that I am using can handle the load of the nRF9160. What I wanted to do is tie the two “USB” pins together, and I noticed there is a diode that prevents powering FROM the USB pin, from the direction of the diode it only OUTPUTS the USB power from the nRF9160’s USB connector to the USB pin on the header.

Note, USB pin refers to JP2 pin 3, 5V0 tagged on the schematic.

What I resorted to is using a micro USB connector and plugging it in, this connector is connected to the “USB” pins on the Feather M0 to power the Feather nRF9150’s 3V3 regulator.

Not sure if it is a good idea to remove that diode, or maybe provide a couple pads on the bottom to solder bridge to bypass the diode if someone wants to backfeed power into the “USB” pin on the header to provide power to the Feather nRF9160’s 3V3 regulator.

Correct me if I am wrong here, but it appears the only way to power the Feather nRF9160’s 3V3 regulator is through the micro USB connector (or battery connector). I don’t dare feed 5V0 into that battery connector, I don’t think the charging IC will be happy with me.

aldras

One more note, the “enable” pin, JP2 pin 2, also can’t be tied to the Feather M0, it might be opposite to the function of the M0’s enable pin. It appears to cut power, I didn’t really investigate this, I just removed the connection from the Feather nRF9160 to the Feather M0 on the “enable” pin.

More and more I am isolating more pins, might just be better to fully isolate the two boards and only connect the needed power, reset, and UART pins…

If it is not apparent already, I am using one of the Feather Tripler boards…
https://www.adafruit.com/product/3417

aldras

Was running into some funny problems (nRF9160 self-resetting for some reason), so I went ahead and isolated all pins except the necessary power, reset, and UART pins. This is the better way to do it anyway so I don’t have signals traveling between the MCUs that I am not sure about.

aldras

This is a reply to the post in https://community.jaredwolff.com/d/66-issue-entering-bootloader-in-new-v2-board asking about the JPEG encoding. I started to type this reply there and realized it might be better to have it here. Left a link there for it directing to here.

If you want to get setup I do have something kinda working, but with HTTP only, no HTTPS support yet.

I basically found some project of someone who made a JPEG compressor for M0 (and works with M4).
The M4 is not really optimized for this (takes a few seconds for a 160×120 color image), but I think if the FPU and some hardware support is combined it will work out faster.

Need to hold the whole raw image in SRAM (or external memory) for the JPEG compression, it jumps around the data while calculating things. A 160 × 120 image comes in at 38400 (160 * 120 * 2) bytes. The resulting JPEG comes in under 10000 bytes, plus some more SRAM used by the JPEG encoding engine itself. I wanted to do 320×200 but it takes more like 128000 SRAM for the raw image, and with the M4 having only 192k SRAM this does not look like it will work. Adding some external SRAM might work, but external SRAM access time will be slow, if you got any ideas it be cool to even be able to do a full 640×480 image!

Give me a little time to get organized and I will get a zip package setup and uploaded for ya to look at soon.

Here is what you need, if you have it already great!
If not, maybe you can sub some other things.
I will work on getting a guide made soon.

Adafruit m4 Grand Central (need all that extra SRAM, and the camera support)
- https://www.adafruit.com/product/4064
Adafruit 1.8″ TFT screen
- https://www.adafruit.com/product/802
- An LCD screen makes it more fun, can download and view images too
OV7670 camera, can find it on Amazon
- Refer to this guide to see which OV7670 board will work
- https://learn.adafruit.com/adafruit-ov7670-camera-library-samd51

K2AAE

“ if you got any ideas ” I was looking into compressing data before transmission but the memory in MCU processors stopped that. I did find that Maxim Integrated makes the MAX32651 and MAX32652 3MB flash, 1MB SRAM:
https://www.maximintegrated.com/en/products/microcontrollers/MAX32651-EVKIT.html The price on the huge low power MCU is $7@1K or $16@1

aldras

K2AAE
Oh thanks, I will keep those in mind.
My attention switched for a moment over to the ESP32 series, since thats what someone at work wants to work with, I have feelings in both directions with the ESP32 line, mostly reliability concerns if its used in a production environment, however the ESP32-CAM (easy to find on Amazon) has 4MB of PSRAM, plus it has some kind of hardware support for JPEG compression.

I get a fully compressed JPEG image from the camera’s buffer somehow, it has to have some hardware assistance for how “instant” the JPEG image is available.

This is another project I will post up soon, it is related to this since its still using the nRF9160 to push the image data to the web, however with the ESP32-CAM I can get a nice 1600 × 1600 image that is around 100k, give or take some bytes depending on the compression. It takes a few seconds to upload but the ESP32-CAM is nice in the way the JPEG is already done for you.

K2AAE

aldras Hardware JPEG codec ST AN4996 app note coupled with that MAX display which is daylight readable would be fun.

aldras

K2AAE
Oh this looks cool, found the application note…

https://www.st.com/resource/en/application_note/dm00356635-hardware-jpeg-codec-peripheral-in-stm32f7677xxx-and-stm32h743534555475750a3b3b0xx-microcontrollers-stmicroelectronics.pdf

This would require a change if platform though, something to keep in mind for a project, thanks!

aldras

I have a partially completed guide up on my blog site using the ESP32-CAM and the Feather nRF9160 to upload JPEG images to a PHP script on a webserver. There are images and source code available. It is using Arduino with the TinyGSM library. The required nRF9160 precompiled firmware .hex files are also linked there with version for JTAG nrfjprog programming and also bootloader programming (if the bootloader will load load the large file).

Once I get the guide more towards completion Ill get some pictures and other information up in this thread soon. A lot of details are really really lacking right now, but wanted to get the project source files up for those interested.

https://www.drassal.net/wp/index.php/2021/02/03/nrf9160-esp32-cam-jpeg-image-uploader-through-lte/

Still working on the M4 version of this project, and working on better TinyGSM support.

jaredwolff

aldras this is awesome. Alright if I share it?

aldras

jaredwolff
Of course! Feel free to share or use any of the information/images posted there.

aldras

Just pushed an update for Arduino TinyGSM library with the updated ESP32-CAM example.
There are detailed instructions on how to hook things up at the top of the example sketch code.
It will show up on the examples menu for TinyGSM.

https://github.com/aldras/TinyGSM/tree/nrf9160_dev

Just remember to set your server address where www.yourServer.net is and remember your APN authentication information. ESP32-CAM board are plentiful and cheap on Amazon.com, but I would buy a few incase you end up with a bad one (most are in the range of $10-$20 each depending on supplier), I have run into a bad one, and another board that the “brownout” detect is kinda finicky.

This should be more stable and works with the fixes done to the TinyGSM nRF9160 support.
The prebuilt firmware is in the example folder for the examples/HttpClient_nrf9160_adafruit_m0_m4 example project.

The updated M4 camera example is coming soon, still trying to get all the code organized.

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