Diamond Systems GPIO-MM-XT 64-Line Digital I/O + 10 Counter/Timer PC/104 Module

Many PC/104 systems in service still run code written for older Diamond Systems counter/timer and digital I/O boards, and replacing two boards with one should not mean rewriting the application. The GPIO-MM-XT is the base build in the GPIO-MM-XT series: an FPGA-based PC/104 digital I/O module that combines the features of the QMM-5/QMM-10 and the GMM-48 on one board, with identical register maps.

The board is built around a Xilinx Spartan II FPGA with 200,000 gates, loaded from on-board flash at power-up and field upgradeable over a JTAG cable. In this personality the FPGA implements 48 programmable I/O lines on 8255 cores in ACB/DFE port order, eight fixed inputs, eight fixed outputs and two 9513 counter/timer cores with five 16-bit counters each. Counters take programmable input sources and output waveforms, count up or down, run one-shot or continuous and generate PWM, and they cascade to 32 bits or wider from a 40 MHz clock.

Three I/O connectors carry 100 pins in total. The right-side connector duplicates the QMM-10 I/O connector and adds ESD protection, while the left-side connector gathers all 48 GMM-48 lines on one header with high-drive buffers sinking up to 64 mA per line and jumper-set pull-up or pull-down resistors. Every line powers up as an input. The GPIO-MM-12-XT keeps the same features in ABC/DEF port order, and the GPIO-MM-21-XT trades the counters for 96 digital lines.

The GPIO-MM-XT runs from a single +5 V supply and operates from -40 to 85 °C as standard. It stacks on the 16-bit PC/104 ISA bus of hosts such as the HELIOS and ATHENA IV SBCs, with two programmable interrupts, eight diagnostic LEDs that show the loaded personality and a 256-byte EEPROM for user data. Diamond’s free Universal Driver software supports every function.