Fast PICUSB CDC example
Many people from Microchip USB forum complained about low transfer speed of new 18F4550/2550/...
devices. Here is an example how to achieve speed of 128kB/s with Microchip CDC firmware (PIC18F4550 firmware
+ Borland Builder 6 application).
fastPICUSB_CDC.rar (76kB)
.zip version (119kB)
Solution:
- transmit 128B buffer each time in ProcessIO routine,
- use multi-threaded PC application (for your own convenience only;),
- request large amounts of data with ReadFile in PC program (in this example I use ReadFile(hComm, &(buffer[index]), 5000, &dwBytesRead, NULL)).
None of my serial terminal emulators was able to receive data from PIC at this speed, probably because they make requests for only 1byte data each time.
Note that this example was made only to prove the possibility of quite fast data exchange - it is rather buggy probably;). Please mail to ot(at)epf(dot)pl if you have installation problems.
Some of usefull I hope code I used with PIC18 micros: library for 25AA640 EEPROM memory CRC8 calculation (poly: x^8 + x^2 + x^1 + x^0, bytewise) not efficient USB TX FIFO - just for convenience
