Diamond Systems GPIO-MM-XT PC/104 Digital I/O and Counter/Timer Modules for Embedded Systems

Digital I/O requirements change over the life of a system: a counter added here, more status lines there, a custom pinout for a new harness. Fixed-function boards force a hardware change each time. The Diamond Systems GPIO-MM-XT series handles this with an FPGA at the centre of each PC/104 digital I/O module, so the same hardware can carry different feature sets, which Diamond calls personalities, that define its functions and connector pinouts.

Every GPIO-MM-XT module uses a Xilinx Spartan II FPGA with 200,000 gates and 40K bits of RAM, clocked at 40 MHz. The FPGA code lives in on-board flash and loads automatically at power-up, and new code can be downloaded over a JTAG cable, which is how custom designs are supported. Three I/O connectors provide 100 pins. The right-side connector includes ESD protection, while the left-side connector uses high-drive logic buffers, sinking up to 64 mA per line, with jumper-configured pull-up or pull-down resistors. All lines start as inputs at power-up. Each board also has two programmable interrupts, a 256-byte EEPROM for user data, jumper-selectable base address and DMA level, and eight diagnostic LEDs that show which personality is loaded.

The series offers three off-the-shelf personalities. The GPIO-MM-XT is the base model with 64 GPIO in ACB/DFE port order and ten 16-bit counter/timers on two 9513 cores, combining the QMM-5/QMM-10 and GMM-48 boards with identical register maps, so earlier Universal Driver applications run without changes. The GPIO-MM-12-XT has the same 64 GPIO and ten counters in sequential ABC/DEF order for new designs. The GPIO-MM-21-XT drops the counters to provide 96 programmable digital lines in ABC/DEF order, 48 on each connector.

All three GPIO-MM-XT models run from a single +5 V supply, operate from -40 to 85 °C as standard and stack on the 16-bit PC/104 ISA bus of Diamond hosts such as the HELIOS, ATHENA IV and ARIES SBCs. Counters offer programmable sources and waveforms, up or down counting, one-shot or continuous modes and PWM, and cascade to 32 bits or wider. Typical uses include industrial control, test equipment, pulse generation and event counting, and the replacement of older two-board counter and digital I/O stacks with one Diamond Systems module.