Project Zeta - MCU
Project Zero : The MCU (Programmer) To begin the design and creation of the project I worked on the base board of the design.. The Microcontroller, an Atmega 2560 was chosen to form the programmer and interface to the whole system primarily because of its large pin count and also I happened to have a few left over from a previous project. The Atmega is configured to run from its internal 8Mhz oscillator and to also output this out the CLKOUT pin so that later on this can be used to provide the system clock to the Z80, this is switched with a GPIO that can be used for single stepping support via a 74AC157 Logic gate. Almost all of the connections on the Atmega are used for the CPU bus and associated lines, this ties up 34 pins of GPIO on the Atmega. The Address bus and data bus are arranged such that they fall neatly on the ports of the atmega so that we can directly write bytes to the ports directly without any bit fiddling. ...