Introducing the RFM22/23, Big brothers to the RFM12B

My sample order of the RFM22 were waiting for me when I arrived home late last night.

Here is a picture of the RFM22 (Left) next to the RFM12B (Right). Pretty much the same physical size, but more pins, and a lot of very small discrete components.

RFM22 and RFM12B

So What’s New?

These new transceiver modules from HopeRF appear to be based on Silicon Labs Si4431 and Si4432 RF Chips. Silicon Labs purchased Integration, from where the RFM12B were based on their EzRadio Series of transceiver chips.

It looks like there are a heap of new feature available, (too many to list here), including some onboard lower MAC smarts called EzyMac, while not as nice as the 802.15.4 MAC layer it looks like it can simplify things such as:

  • Automatically adding pre-amble and sync bytes.
  • Automatic packet size – you just push bytes into the Tx FIFO and it will create the packets of a fixed size and send for you.
  • Built in basic frequency hopping.
  • Built in Data Whitening, Manchester Encoding, and CRC

Some more niceties:

  • 64Byte FIFO.
  • Onboard A/D, allows access to read such things as an onboard Temperature Sensors, Voltage buses.
  • x2 configurable GPIO ports.
  • More Rx Sensitivity than the RFM12B.
  • More Tx power than the RFM12B
  • Lower Operating voltage.
  • 8bit RSSI value.
  • Three different modulation schemes to select from.

Some not so niceties:

  • More current draw on Rx than the RFM12B.
  • More current draw on Tx than the RFM12B (understandable seeing it also has a higher Tx Power).
  • Costs about twice as much as the RFM12B ~ $USD6.00 in sample quantities direct from HopeRf vs ~$USD3.00 for the RFM12B.
  • Heaps more commands/Registers to learn.
  • No onboard encryption.

Feature comparison:

Voltage 2.2-3.8V 1.8-3.6V 1.8-3.6V
Max Data Rate 115.2kbps 1-128Kbps 1-128Kbps
Max Power Output (Tx) 5dBm@433MHz 3dBm@868MHz 3dBm@915MHz 17dBm@315MHz 17dBm@433MHz 17dBm@868MHz 17dBm@915MHz 13dBm@315MHz 13dBm@433MHz 13dBm@868MHz 13dBm@915MHz
Sensitivity (Rx) -105dBm@433MHz -102dBm@868MHz -102dBm@915MHz -118dBm@315MHz -118dBm@433MHz -118dBm@868MHz -118dBm@915MHz -118dBm@315MHz -118dBm@433MHz -118dBm@868MHz -118dBm@915MHz
Max Supply current (Tx) 22mA@433MHz 23mA@868MHz 24mA@915MHz 80mA@315MHz 80mA@433MHz 80mA@868MHz 80mA@915MHz 28mA@315MHz 28mA@433MHz 28mA@868MHz 28mA@915MHz
Max Supply Current (Rx) 11mA@433MHz 12mA@868MHz 13mA@915MHz 18.5mA@315MHz 18.5mA@433MHz 18.5mA@868MHz 18.5mA@915MHz 18.5mA@315MHz 18.5mA@433MHz 18.5mA@868MHz 18.5mA@915MHz
Standby Current ≤0.3uA ≤0.01uA ≤0.01uA
FIFO 16bit 64byte 64byte
Frequency Resolution 2.5-7.5kHz 156.25-312.5Hz 156.25-312.5Hz
Low Battery Detect Yes Yes Yes
Temperature Sensor No Yes Yes
Frequency Hopping Capable Yes Yes Yes
Wideband or Narrow Band Design Wideband Wideband or Narrowband Wideband or Narrowband
RSSI No Yes Yes

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Author: Stephen Eaton

Geek at heart. Loves to tinker and find out how things work, which inevitably leads to items in pieces and not working for much longer :)

2 thoughts on “Introducing the RFM22/23, Big brothers to the RFM12B”

  1. 🙂 Waiting for you to share the RFM22 love.

    Let me know when you do a range test on these critters and I’ll really like to know the range on the low frequencies.

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