The PMX42 is a design concept I came up with for a 1/8 DIN size computing module with a 128×64 amber OLED display. It’s not really a “meter” in the classic sense, but an open architecture computing module nucleus that accepts custom I/O cards to meet a wide variety applications. In effect, the I/O cards and firmware define the application and it’s use. So, for now, we’ll dub this module as the “Accelerating Product Development Nucleus“!
The PMX42 has lots of horsepower under the hood and is powered by a powerful Texas Instruments Tiva TM4C1294NCPDT ARM® Cortex™ M4F microprocessor. The Tiva processor operates at 120-MHz and achieves 150 DMIPS performance while providing 1024 KB Flash memory for code and 256 KB single-cycle system SRAM for dynamic memory use.
The onboard peripherals includes a 10/100 Ethernet MAC, USB 2.0 OTG, SD memory card slot and option slot for internal WiFi or Bluetooth card. The PMX42 also provides on-board power and regulation to provide 3.3V, 5V and +/-12V to each I/O card slot on the motherboard.
Each slot contains I/O pins to the Tiva’s quad synchronous serial interface (QSSI) modules with advanced high speed quad SSI support. The first two slots are wired to one SSI controller and the second two slots are wired to a second SSI controller. Each slot has it’s own dedicated interrupt and slave select line wired to the processor GPIO’s. Additional multifunction GPIO’s are available on each slot as well. Slots 3 & 4 have dedicated high speed UART and serial lines to support a variety of communications options.
CUSTOM DESIGNED SHEET METAL ENCLOSURE
The entire PMX42 enclosure and boards were all 3D modeled and designed in Geomagic by 3D Systems. All of the sheet metal pieces in this design were laser cut and formed to tight tolerances (within 5 mil) by PCI Pro Coaters Inc right here in Atlanta Georgia. Give the guys at PCI a call if you need any professional sheet metal work done – they do amazing work and are the best folks around!!
RS-232/422 DUAL SERIAL I/O CARD
One of the first cards I designed was a generic RS-232 and RS-422 high speed serial card. The RS-232 is supported by the MAX3223 and supports speeds up to 250kbps with CTS/RTS flow control. The full duplex RS-422 port is supported by the SN65HVD1473D part with data rates up to 20Mbps.
BLUETOOTH I/O CARD
A Bluetooth I/O card is available also which uses an off the shelf module for ease of integration. The Bluetooth module communicates to processor via a high speed UART interface.
SMALL SIGNAL RELAY & OPTO INPUT I/O CARD
The small signal relay card provides two SPDT relays for low-level switching and signal control. It also features three opto-isolated inputs that can be used to trigger from external events by pulling the inputs low to ground.
DUAL RTD TEMPERATURE I/O CARD
A dual 3-wire RTD temperature measurement card using Analog Devices AD7793 ADC’s in the works also. The AD7793 is a 24-bit low power, low noise, complete analog front ends for high precision RTD temperature measurement applications.