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README.md

@@ -1,2 +1,27 @@
 # LoRaTransmit
+
 LoRa packet transmitter for RNode hardware 
+
+## Usage
+
+provide payload as command line argument or via pipe
+
+```
+usage: loratransmit [-h] [--freq Hz] [--bw Hz] [--txp dBm] [--sf factor]
+                       [--cr rate]
+                       [port] [payload]
+
+LoRa packet transmitter for RNode hardware.
+
+positional arguments:
+  port         Serial port where RNode is attached
+  payload      The payload to be transmitted
+
+options:
+  -h, --help   show this help message and exit
+  --freq Hz    Frequency in Hz
+  --bw Hz      Bandwidth in Hz
+  --txp dBm    TX power in dBm
+  --sf factor  Spreading factor
+  --cr rate    Coding rate
+```