There is conflicting information about the power consumption of the NRF24L01+ PA LNA breakout boards. Perhaps some boards leave some circuitry powered on all the time even when the NRF24L01+ is sleeping while others do not. This little experiment was to determine current consumption for some of the radio's different states, especially during NRF and microprocessor sleep states, for the purpose of creating power budgets.
Setup was an Arduino Nano clone.3.3VDC from an AMS1117vreg to an NFR24L01+ PA LNA from Ebay (link). Meter was a UNI-T UT61E. TMRh20's RF24 library was used.
Mode ... Current Consumption @ 3.3VDC
radio power up = 0.030 mA radio power down = 0.00054 mA (0.54 µA)
stop listening = 0.031 mA start listening = 20.7 mA write (pa_max, 250kbps) = 140 mA
power on, no init, USB plugged into PC = 0.47 mA power on, no init, atmega sleep, USB plugged into PC = .130 mA power on, no init, USB plugged into charger = 0.43 mA power on, no init, atmega sleep, USB plugged into charger = .06 mA
2.7V BOD/8Mhz Int Oscl Moteino Variant Put in the Moteino boards.txt The "extended_fuses" has been changed from 0xFD to 0x05 because the USBASP throws an error when burning the bootloader.
The boards* are in and ready to be populated with the proper components listed on the BOM whatever i can find in my scrap bin. For the very first assembly, I'm using female headers on the Tiny board so i can easily remove it from the Arduino Nano in case something goes wrong.
So I've exhausted my supply of female headers so the first assembly looks a little lame. But it works. And since it works, one should know that this board has no voltage regulation and no polarity protection diodes of any sort. So be careful!
Programming
The ATTiny isn't supported out of the box by the Arduino IDE, but MIT's hi lo tech has a handy-dandy tutorial for adding the ATTiny support and programming it. To program the ATTiny, the Nano first needs to be programmed to be an ISP. The RST cap on the Tiny board is disabled by 1) moving the jumper to the position closest the USB connector or 2) removing the jumper altogether. The ArduinoISP sketch can be uploaded and the RST cap moved back to enable programming the ATTiny. A note on clock settings and fuses: If you want your ATTiny to run at a specific clock speed, select the desired frequency under Tools - Clock and then under Tools - Burn Bootloader which sets the approriate fuses. Once the fuses are set, you can upload your sketch. If you switch the clock speed without "burning the bootloader" and upload a sketch, your timings might be off, e.g. a 1 second delay is now 8 seconds or vice versa.
Features
The red LED is for the ArduinoISP heartbeat and is a breakout of the
Nano's D9 pin. The green LED is an onboard LED for the ATTiny and connected to
D3 (not D1), see bright green highlight. This LED can be disabled by the nearby jumper. There's a
3.3/5Vvoltage selection jumper (blue highlight) for when this guy is attached to the Nano.
Again, there's no voltage regulation/protection apart from the Nano's.
2x 3mm LEDs 2x 220 Ohm Resistors 1x 10uF Capacitor, Radial 1x Momentary Tactile Switch 1x ATTINY85-DIP (Digi-Key AE10011-ND) --------- *I used OSH Park's new 2 Layer 2oz 0.8mm Service because I'd never used it before. The board is nice and thin, alignment and silk both look great as usual.
So layout went rather quickly on this one because it's pretty simple and I have too much fun doing this. Actually, the board is already on order with OSH Park. I took some (read a lot of) design cues from Kevin Rye's ATTiny Programmer. Among other things, I liked the LED disable jumper, the IO breakout headers and the idea to create a programming board that one can also use in a project. I elaborated on the IO breakout by adding V+ and GND headers. Maybe it will be useful, maybe not. I also added a jumper to selected 3.3V or 5V and another to enable/disable the 10uF cap on the Nano's RST pin. There's also a dedicated RST switch for the ATTiny. The overall profile mimics the Nano's with an extension opposite the USB connector on the Nano. So here's the final design ... And the schematic ... Now I play the waiting game ... and discover where I screwed up. Which was ignoring a poorly placed via and at least one silkscreen mislabel. In the meantime, I've learned how to cover the vias with soldermask using Masks tab in the DRC. The final-er design is below.
