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Serial UART to nRF8002 to Bluetooth 4.0 service

Peter Burkimsher

Hi Nordic Devs,

First, thank you for excellent documentation and sample code for use with your hardware. It's been tremendously useful already!

I'm pleased to own an nRF8002 Bluetooth LE chip, mounted on a proximity tracker (iCookie). I've soldered onto the test points, and made a breakout board for the serial UART.

Now I'd like to use the serial connection to send some data that will be transmitted as a characteristic of a Bluetooth 4.0 service.

I can see the nRF8002's broadcast services using LightBlue on my MacBook Pro. itunes.apple.com/.../id639944780

To communicate with the serial line, I have 5 options.

  1. My Raspberry Pi has 3.3V GPIO ports, including UART as an option.
  2. I have an old Toshiba laptop with a DB9 serial connector. I think that uses 5V.
  3. I have a SystemBase USB to RS422/485 adaptor. systembase.co/.../
  4. I have a CANUSB USB to serial adaptor. www.can232.com/
  5. I have a COMS USB to 485 adaptor. www.ebay.com/.../231089860247

As far as I can tell from the datasheet, the nRF8002 uses 3V levels, which means only the Raspberry Pi is safe to use. Can you confirm that?

I don't have a MAX3232 serial level converter, unfortunately, but I am looking to find one. If I get a voltage converter, would it be possible to then make the UART work with one of my serial adaptors, or the old Toshiba laptop?

nRFgo Studio only works on Windows. Do you have any suggestions for the Raspberry Pi?

I have 7 days to figure something out, but my equipment is limited to what I listed above.

I'm not trying to reverse-engineer the iCookie. The goal of this project is to make a wireless kitchen scale, which will require interfacing the weighing scale sensor-SPI-adaptor/Raspberry Pi-UART-nRF8002-Bluetooth-mobile app. The iCookie was selected by my manager as a cheap way to get access to a Bluetooth 4.0 chip.

Please let me know if there's anything you can suggest!

Peter Burkimsher

  • 0 in reply to David Edwin

    Thank you for the suggestion! I'm pleased to see that it's also supported by the nRFready iOS demo app, and is still low-power. In the morning I'll solder some wires onto the scales I've got, and see if I can make any sense of SPI data. There's a 4-wire header with VDD, Key1, Key2, and GND, which I guess might be SPI. The chip in the scales is all covered in epoxy though, so I can't be certain. Ultimately the final design will be using our own weight sensors and everything, I just want to be able to build a prototype to keep my manager satisfied.

    Meanwhile, please can you confirm that plugging in the chip to a DB9 serial COM port is unsafe? I'm pretty sure from the datasheet that 5V would fry the nRF8002, but it would make building the programming circuit much easier.

  • 0 in reply to David Edwin

    Remember I am talking about the nRF8001 , NOT the nRF8002. You will need to get a BLE shield as stated in the devzone.nordicsemi.com/arduino As for the weighing scale, the last time we hacked at it we intercepted the display (which was displaying the weight) , interpreted it and sent it over the BLE link.

  • 0 in reply to David Edwin

    Yes, I will try to persuade my manager to buy more hardware when I've proven that I'm able to use what I have responsibly. Interfacing with the display bits might be easier, because I'm not certain if the epoxied chip is really showing an SPI port, or some other test points.

    I really appreciate all the project-specific help, and hope that we can continue to work on this. I've installed nRFgo Studio on the old Toshiba with the DB9 COM port, and the software is working fine. However, I'm afraid to plug it into the current chip I have. I know it's not the final development board we'll be using, but it really would be nice to show something practical to my manager rather than just a comment thread. If the 8002 is 5V safe, all will be well! But please confirm this, because I understand the datasheet to say that it's only able to run at 3V levels.

  • 0 in reply to David Edwin

    I will be very surprised if the UART lines on the iCookie work, as nRF8002 devices will lock off the UART once they have been production programmed (like in the iCookie). The nRF8002 works between 1.9v to 3.6v it is not 5v safe. You may be able to re-use the button on the iCookie and then interface the button to the scale so when somebody steps on the scale the alert is sent to the phone.

    I really do not know the chip in the scale so I cannot comment on it at all. Good luck.

  • 0 in reply to David Edwin

    Ah, it's locked off after one-time programming? Then I guess there's not much I can do. Thank you for explaining! I'm glad that I correctly understood the datasheet about it not being 5V safe. Even though I'm obviously a bit disappointed that I soldered a beautiful breakout board for the test points, I'm extremely impressed by Nordic's technical support. Seriously - many companies are actively hostile to people modding and tweaking their equipment, but you've been actively helpful in guiding me how to do this correctly! Happy lunar new year!

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