I’ve just received a pair of nRF24L01+ radio modules for my Arduino and have been learning how to use the RF24 library.

Probably the hardest part was getting the ATmega328P running at 3.3V/8MHz on the breadboard. Funny shenanegans went on that meant I had to burn the bootloader using ArduinoISP with a 16MHz crystal and pair of 22pF caps, then remove them and upload the sketch using my CP2102.

Anyway, after figuring out that “RF24 radio(9,10);” referred to the CE and CSN pins respectively on the module being wired to digital 9 and 10 on the Arduino, things started working.

Some new components I’ve got on order, I’m trying to find a way to wirelessly connect devices using RF instead of the more expensive and limited range of WiFi.

• ✔ 2x nRF24L01+ 2.4GHz Antenna Wireless Transceiver Modules – for wireless comms between my Arduino and Raspberry Pi
• ✔ HC-SR04 ultrasonic distance sensor – as the one I ordered before never arrived
• ✔ 2x 433MHz RF transmitter/receiver pairs – alternatives to the RF24’s, I can’t get them working though
• ✔ Beagle Bone Black – well it was 10% cheaper than anywhere else
• ✔ Raspberry Pi Camera Board – now I need a mount for it
• ✔ 2x 8GB MicroSD card – 30MB/sec models for the BBB/Raspbmc
• ✔ USB ISP and 6-pin adaptor – for programming ATtiny’s without an Arduino. Will probably take a while as Paypal fucked up.
• ✔ 20x 2.1×5.5mm DC barrel jacks – breadboard-friendly
• ✔ 10x 8MHz crystals – as I seem to be having problems uploading sketches at 3.3V/8MHz
• ✔ 2x nRF24L01+ PA+LNA modules with antennas – longer range versions of the above modules
• ✔ 10x single-row 40-pin female headers
• ✔ 10x double-row 40-pin female headers
• ✔ 2x waterproof DS18B20 temperature sensors on cables
• ✔ 2x DHT11 temperature/humidity sensors
• ✔ 2x BMP085 barometric pressure sensors
• 3xAA and 4xAA battery holders
• 2x project boxes

I’m going to get a Spark Core when they’re available in the UK hopefully next month, and maybe a Flutter Pro

I’ve been having some weird crashes on my Debian Sid box over the last couple of days, which seems to be due to an ancient Nvidia bug, reports of which seem to go back to the 295 drivers from 2010, I’m getting problems with the 304 and 325 drivers!

[20638.158211] NVRM: GPU at 0000:01:00: GPU-a71588bd-1a44-5686-1d67-fbad1976d394
[20638.158217] NVRM: Xid (0000:01:00): 13, 0001 00000000 0000e495 000007e4 00000000 00000090
[22520.926368] NVRM: GPU at 0000:01:00: GPU-a71588bd-1a44-5686-1d67-fbad1976d394
[22520.926374] NVRM: Xid (0000:01:00): 13, 0001 00000000 0000e495 00001264 000001a5 00000080
[24428.921381] NVRM: Xid (0000:01:00): 13, 0001 00000000 00000302 00000100 8e7844a0 00000000
[24428.922286] NVRM: Xid (0000:01:00): 13, 0001 00000000 00000302 00000100 8e7844a0 0000ffff
[24430.922272] NVRM: os_schedule: Attempted to yield the CPU while in atomic or interrupt context
[24432.922317] NVRM: Xid (0000:01:00): 12, COCOD 00000001 e0012d00 0000502d 00000100 8e7844a0
[24432.985365] NVRM: Xid (0000:01:00): 13, 0001 00000000 00000302 00000100 8e7844a0 00000000
[24433.051974] NVRM: Xid (0000:01:00): 12, COCOD 00000001 e0012d00 0000502d 00000100 8e7844a0
[24436.972661] NVRM: Xid (0000:01:00): 13, 0001 00000000 0000e495 000018f8 00000000 00000090

So I decided to try the opensource Nouveau drivers instead of Nvidia’s proprietary crap:

I’ve added a Darlington Array to my gearshift project, so that eventually it will drive 3 relays which in turn will drive 3 solenoids to change gear on the motorbike.

I love the way the ULN2803A works as its so simple – the inputs on the left go to the same outputs on the right, no code, no SPI, just feed it the outputs from the ATtiny.

If you look at the video you can see that’s I’ve also added a 7805 circuit to bring the 12V bike battery or 9V battery I’m using currently down to 5V for the Arduino and relays. Update: now moved to veroboard: video 2 layout.

Instead of being sheepish and using an RTC shield, I decided I’d knock up an RTC module myself, its incredibly simple anyway – just a 32.768KHz crystal, a DS1307 chip and a 3v coin cell battery. It talks I2C so only two wires to connect to the Arduino (plus two for power):

If you’re using another I2C device, you should put a 10k pullup resistor on SDA and SCL, and a 0.1uF capacitor on the Vcc if you’re anal about power smoothing.