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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

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  • 0

    If you are looking at a serial interface you can also look at the nRF8001 that provides a well defined serial interface (SPI) and you can use an Arduino to control the nRF8001. See devzone.nordicsemi.com/arduino Making a weighing scale with Arduino and the nRF8001 should be easy using the nRFgo Studio for nRF8001 configuration.

  • 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.

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  • 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.

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