User's Manual

PMAC2 PCI Lite Hardware Reference Manual – Preliminary Documentation
Hardware Setup 5
HARDWARE SETUP
Watchdog Timer Jumper
Jumper E19 must be OFF for the watchdog timer to operate. This is an important safety feature, so it is
vital that this jumper be OFF in normal operation. E19 should be put ON only to debug problems with
the watchdog timer circuit.
CPU Frequency Control Jumpers
If variable I46 is set to the default value of zero, jumpers E2 and E4 on the base PMAC2 PCI Lite board
control the frequency at which the CPU will operate (or attempt to operate). Generally, this will be the
highest frequency at which the CPU is rated to operate.
• If jumpers E2 and E4 are both OFF, the CPU will operate at a 40MHz frequency.
• If E2 is ON and E4 is OFF, the CPU will operate at a 60MHz frequency.
• If E2 is OFF and E4 is ON, the CPU will operate at an 80MHz frequency.
• If I46 is set to a value greater than zero, E2 and E4 are not used. The CPU frequency is set to 10MHz
(I46+1)
Re-Initialization Jumper
If E3 is off during power-up/reset, the controller will load its last saved set-up parameters from flash
memory into active memory. This is the setting for normal operation.
If E3 is on during power-up/reset, the controller will load its factory-default set-up parameters from
firmware into active memory. Generally, this is done only if communications cannot be established with
the card when it comes up in normal operational mode.
Power-Up State Jumpers
Jumper E20 must be OFF, jumper E21 must be ON, and jumper E22 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.)
Firmware Load Jumper
If jumper E23 is ON during power-up/reset, the board comes up in bootstrap mode which permits the
loading of new firmware into the flash-memory IC on the board. When the PMAC Executive program
tries to establish communications with a board in this mode, it will detect automatically that the board is
in bootstrap mode and ask what file to download as the new firmware.
Jumper E23 must be OFF during power-up/reset for the board to come up in normal operational mode.
Flash Memory Bank Select Jumpers
The flash-memory IC in location U10 on the Flex CPU 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 E10A, E10B, and E10C 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.
Encoder Sample Clock Source Jumpers
Jumper E13 controls the source of the SCLK encoder-sampling clock for each servo IC. The default
setting, No Jumper Installed, means that the SCLK signal comes from the servo IC and is output on the
JMACH connectors. This setting is suitable for all but a few special applications.