PMAC2A PC104 Hardware Reference Manual
CPU Jumper Configuration
E15A-E15C: Flash Memory Bank Select Jumpers – The flash-memory IC in location U10 on the PMAC2A PC/104 base board has the capacity for eight separate banks of firmware, only one of which can be used at any given time. The eight combinations of settings for jumpers E15A, E15B, and E15C select which bank of the flash memory is used. In the factory production process, firmware is loaded only into Bank 0, which is selected by having all of these jumpers OFF.
E10-E12:Power-Up State Jumpers – Jumper E10 must be OFF, jumper E11 must be ON, and jumper E12 must be ON, in order for the CPU to copy the firmware from flash memory into active RAM on power- up/reset. This is necessary for normal operation of the card. (Other settings are for factory use only.)
E14: Watchdog Timer Jumper – Jumper E14 must be OFF for the watchdog timer to operate. This is a very important safety feature, so it is vital that this jumper be OFF in normal operation. E14 should only be put ON to debug problems with the watchdog timer circuit.
W1: Flash chip select – Jumper W1 in position 1-2 selects a 28F320J3A part for the U10 flash chip. Jumper W1 in position 2-3 selects a 28F320J5A part for the U10 flash chip. This jumper is installed in the factory and must not be changed from its default state.
Communication Jumpers
E18-E19: PC/104 Bus Base Address Control – Jumpers E18 and E19 on the PMAC2A PC/104 baseboard determine the base address of the card in the I/O space of the host PC’s bus. Together, they specify four consecutive addresses on the bus where the card can be found. The jumpers form the base address in the following fashion:
E18 | E19 | Address (hex) | Address (dec) |
OFF | OFF | $200 | 512 |
OFF | ON | $210 | 528 |
ON | OFF | $220 | 544 |
ON | ON | $230 | 560 |
The default base address is 528 ($210) formed with jumper E18 removed and E19 installed. This configuration is necessary for using the USB or Ethernet ports of the Acc-2P communications board.
I/O Configuration Jumpers
E16: ADC Enable Jumper – Install E16 to enable the analog-to-digital converter circuitry ordered through Option-12. Remove this jumper to disable this option, which might be necessary to control motor 1 through a digital amplifier with current feedback.
Resistor Packs Configuration
Differential or Single-Ended Encoder Selection
The differential input signal pairs to the PMAC have user-configurable pull-up/pull-down resistor networks to permit the acceptance of either single-ended or differential signals in one setting, or the detection of lost differential signals in another setting.
The ‘+’ inputs of each differential pair each have a hard-wired 1 kΩ pull-up resistor to +5V. This cannot be changed.
The ‘-‘ inputs of each differential pair each have a hard-wired 2.2 kΩ resistor to +5V; each also has another 2.2 kΩ resistor as part of a socketed resistor pack that can be configured as a pull-up resistor to +5V, or a pull-down resistor to GND.
If this socketed resistor is configured as a pull-down resistor (the default configuration), the combination of pull-up and pull-down resistors on this line acts as a voltage divider, holding the line at +2.5V in the absence of an external signal. This configuration is required for single-ended inputs using the ‘+’ lines alone; it is desirable for unconnected inputs to prevent the pick-up of spurious noise; it is permissible for differential line-driver inputs.
