Atmel AVR Infrared Downloader. Part 1. Host-side.
This project makes firmware upgrades easy: The target has an Infrared receiver and the data is sent via IR. The IR transmitter is based on V-USB.
Host program was compiled using Lazarus Freepascal. Device firmware was compiled using WinAVR (AVR-GCC).
Infrared data transmission uses USART facility and Timer2 for 38 kHz modulation signal generator. Baudrate 2400bps is based on the IRM-8510N data reception ability which is 400us for the shortest length logic signal.
With a single infrared led, both host and target side can wirelessly communicate at about 6,5 meters. Final board uses 6 infrared led, can handle 15 meters length approximately.
Data packet size was limited 128 byte length because of ATmega8 SRAM at host-side was limited at 1 kbyte size. During development phase we planned to increase till 1~2 kbyte length but we avoided it. Actually it can be increased to optimize the transfer process using a bigger SRAM AVR series. All transmission packets were implemented using CRC16 for error detection.
Schematic Diagram: Host-device
Host-Side Features are:
Schematic Diagram: IR transmitter circuit
Schematic Diagram: IR receiver circuit
In the following part of the description we will get acquainted with the circuit of the target device which carries out reception of the data and microcontroller In-system programming.
Host-side: schematic diagrams, software for microcontroller and PC: 20081008.host.side.zip
Shematic Diagrams: IR transmitter circuit, IR receiver circuit 20080726.ir.circuit.zip
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