The X-Drive and Y-Drive
6-10 DSX™ System Service Manual
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6.2.4.3. Microcomputer
The XY Module hardware is based around the Hitachi H8/3337F single-chip
microcomputer. This microcomputer provides 60Kbytes of Flash ROM and 2Kbytes of
RAM and operates at 16 MHz. The H8/3337F has the following internal peripheral
capabilities:
9 ports, providing 58 I/O and 8 Input lines
Two 8-bit timers (TMR0, TMR1)
One 16-bit free-running counter (FRC)
Two digital to analog channels (DA0, DA1), with 8-bit resolution
Eight analog to digital channels (AN0 through AN7), with 10-bit resolution
Two serial communications channels (COM0, COM1)
Two pulse width modulation channels (PWM0, PWM1)
6.2.4.4. Port Configurations and Operating Mode
The I/O ports are configured to allow maximum software control of all XY functions
within the limitations of timing and functionality of the H8/3337 and to minimize external
hardware.
To maximize this capability, the H8/3337 is configured in the single-chip mode to allow all
port pins to be available. The “single-chip” mode of operation implies that there are no
external program memory resources available to the software. The entire program must fit
within the confines of the 60Kbyte internal ROM space, and all variables, stack, and heap
space must be restricted to the 2Kbytes of internal RAM.
An external ST93C46CB1 serial EEPROM connected to port P1 is used to store setup and
calibration information for the XY Module.
An MAX705 microprocessor supervisor IC is connected to the Reset input on the H8 to
provide reset on power up.
6.2.4.5. Serial Communications with Controller
Commands and test data are transferred between the H8 microprocessor and the
communications controller via a serial RS-232 interface. Interface drivers and receivers are
used between the COM1 serial communications channel on the H8 microprocessor and the
interface connector to provide proper RS-232 signal levels to the controller.
DSR is signalled via Port 8-6.
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