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RFM23BP Power  XML
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Joined: 03/06/2014 12:30:20
Messages: 1

According to this design reference:
The RFM23BP should be powered at 5V but it's SPI interface will run at 3.3V. This conflicts with the information in the RFM23BP data sheet:
I have been having problems with this in my testing and it looks like the SPI interface is operating at the VCC level (5V). Can you provide any more information?


Joined: 30/05/2014 22:08:56
Messages: 93


The RFM23BP module runs at 5V. However, the gpio and spi control interface reportedly must ONLY be run at 3.3V

Option 1) VCC on the RFM23BP module should be 5V, and VCC on your CPU should be 3.3V.
Don't supply 5V on the SPI pins on the RFM23BP.

Option 2) Power both CPU and RFM23BP with 5V, BUT use level shifting to only supply 3.3V on the RFM23BP interconnect pins.

You might find option 1 easier (just make sure to use separate VCC, and common GND)

Please note the datasheet says the following:
power of the unit, VDD range is 3.3 to 6V
Pins (including SPI control pins) are spec'd at: –0.3, VDD + 0.3
------- I don't believe this is correct, but I should double check with Hope Engr. and post a follow-up -------

Hope this helps.

What SPI mode and clock rate are you using?

This message was edited 1 time. Last update was at 22/06/2014 00:28:22

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