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jdesbonnet / RFMxx_LPC812_PCB

PCB board to experiment with HopeRF RFM69 and RFM98 radio modules. Uses ARM Cortex-M0+ LPC812 as controller.
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Use PullUps for NSS, MOSI, SCK #1

Open JojoS62 opened 6 years ago

JojoS62 commented 6 years ago

nice board. I've built a similiar one, also with LPC812 and RFM69. I'm using it for some sensors in homeautomation. For maximum power saving in deep power down mode, I found that it is necessary to add external pull up resistors of about 47k to prevent the RFM inputs from floating. Without these resistors the idle current was much higher as stated in the datasheet.

jdesbonnet commented 6 years ago

What kind of sleep current are you getting? I think I got mine down to 4uA with the wake-up timer running. Getting it down to that level involved some experimentation with the pin states. I'd be curious to know if you did better?

JojoS62 commented 6 years ago

the wake up timer takes about 1 µA, in total I have 1,3 µA for the LPC812 with self wake up, RFM and a SHT31 temp/moisture sensor. Without self wake up it uses about 0,3 µA. In deep power down, also the pull ups are disabled, this must be considered. Also for the reset pin is a ext. pull up recommended in the LPC user manual.

jdesbonnet commented 6 years ago

Thanks for the tips. I must try get that 4uA down further.

JojoS62 commented 6 years ago

img_0250s you're welcome. On your board, you have some headers for testing, thats fine. I had to add some tombstones to fix it :) I'm preparing my software also for releasing on Github, great to find someone not only using AVRs :)