under construction
APC220 radio
The APC220 radios is one of the simplest ways to implement radio communication between computer devices.
The APC220 provides a simple serial transmit receive interface.
Some specs
Voltage: 5V
Transmit distance up to 1000m (line of sight) @9600 bps
Max TX power 20mW / 13 dBm
Frequency is from 418MHz to 455MHz
256 bytes data buffer
High sensitivity (-112dbbm @9600 bps)
GFSK modulation
UART/TTL interface
Embedded watch dog
Size: 37 x 17 x 6.5 mm (1.46x 0.67x 0.26 in)
micro TX --> RX(APC220) ---radiolink---> (APC220)TX --> RX(another micro)
Forward error encoding handles transmission errors up to a certain level.
Thumb rule says that if you transmit 40 bytes will send up to 80 bytes in air All encoding etc is handled by the radios so the users just see it as a serial wire connection.
Encoding and error correction is handled by the radio so you just have a wireless serial line.
Limitations:
TX bufferoverflow - obvious
Lost connectivity - not line of sight, distance too long, noise, wealk antennas,…
This apc220 interface and configuration library is based on a simple C class
It is based on use of SoftwareSerial so on a UNO the hardware serial port is available or other things.
On a cansat it could be like
hardware serial for logging data on sdcard
higher baudrate than for radio to log large amount of data
57600 which gives 5000 bytes to log pr second
software serial for telemetri back to your homebase
9600 baud or lower (lower for extending range)
a few hundred bytes pr second
Still beware of your databudgets. Dont use all CPU power and time for logging
If you have a MEGA there is 4 hardware serial ports. In that case you can modify library to just use a hardware serial port.
because …
Changing frequency on radio
The library provide a simple interface for reprogram the apc220
See examples
See apc220code.html
Source listnings
list folder: apc220cfg
list folder: apc220serial
Docs
Encoding - in general
Jens
See links in menu at your left