Posts - nerpa.tech

Programming Voltage Limiter for Newer PIC Microcontrollers

Newer PIC18 microcontrollers, such as the PIC18F26K20, are not designed to be programmed with 12V. According to the datasheet, the maximum allowable programming voltage (VPP) of these devices is 9V. However, older Microchip programmers/debuggers like the PICkit and ICD 2 do not support adjustable programming voltage and are only capable of providing 12V VPP. When you create an MPLAB project using a K-series PIC18 and the ICD 2 debugger, you’ll receive a warning along with a suggested VPP limiting circuit schematic. In this article, I describe that very circuit so you can build it in advance.

2009-03-26 by Oleg Categories: Programming, Electronics Tags: MCU, PIC18

Interfacing a Character LCD via SPI

Modern microcontrollers are packed with memory and processing power, but often don't have enough pins for everything we want to connect. A classic example is driving an HD44780-compatible LCD display — a great choice for simple user interfaces, but one that normally demands a lot of I/O lines. In this project, I'll show you how to control one of these displays over a simple SPI connection, using just a handful of wires and a cheap shift register. We'll build a tiny daughterboard to handle the conversion, set up a minimal breadboard circuit for testing, and walk through exactly how to send data to the LCD. Along the way, I'll also point you toward some tools that make experimenting even easier.

2009-03-23 by Oleg Categories: Programming, Electronics Tags: HD44780, LCD, PIC, SPI, MCU