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USB to Serial TTL

For some of my PIC projects I need a serial (RS232) interface to print some messages on the screen of my computer. I still have a desktop computer that has one RS232 interface but nowadays most computers have a USB interface instead. You can buy devices that convert – TTLRS232 signals to USB for which several projects have already been published on Instructables but I decided to build one myself. The reason for that is that I like building stuff but also that this version does not need a special driver for Windows 10 since it uses a standard Microchip device descriptor which is already supported by Windows 10.

Since the requirements for the baudrate may vary I decided to support the following baudrates using jumpers on the board: 9600, 19200, 57600 and 115200. The device always uses 8 bits, 1 stopbit and no parity for its transmission.

As you may know you cannot use TTL signals to drive an RS232 interface so I also created an RS232 board based on the MAX232 chip that converts the signals to the right level. In this Instructables I have also posted the schematic diagram of the RS232 board since I used it for testing my USB to Serial TTL converter.

I used a PIC 16F1455 as device to control the USB port and transfer all data from USB to serial using the JAL programming language.”

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