this bulk loopback firmware based on the firmware frameworks. Loops back EP2OUT to EP6IN and EP4OUT to EP8IN. Building this example requires the full version of the Keil Tools.

This is an MCP2515 driver application using a PIC16F73, connected to the PC through the serial port. In the firmware you can easily configure the MCP in TX, RX or LOOPBACK mode.

1、 由PC机发送一个字符给单片机，单片机收到后，将该字符回送给PC。 2、 由PC机发送一个字符给单片机，单片机收到后，将小写字母转换成大写字母回送给PC机，如果不是小写字母，单片机均回送字符“F”给PC机。 3、 由PC机发送一个字符串给单片机，单片机接收到后将其中的大写“A”字母的个数统计出来，显示在数码管上。-1, the PC sends a character to the microcontroller, MCU receive the characters back to