Print Engine Interface
10-2
MC68322 USER’S MANUAL
MOTOROLA
The print engine interface is capable of sending and receiving information to and from a print
engine, which is done at the same time as all other operations within the MC68322. This
transmission and reception of information is synchronous either to the clock supplied by the
interface or to the clock supplied by the print engine. For transmitting video data, the PVC
can run synchronously from a 1
× video rate from the print engine. If the print engine does
not supply a video clock, the PVC can phase lock to a print engine’s synchronization signal
and generate an internal video rate to use during transmission. The phase-locked loop
circuitry runs off of a clock from an external oscillator.
10.1 PRINT ENGINE INTERFACE REGISTERS
The print engine interface contains several registers that control the engine interface
protocol, signals, and interrupts. These registers include the printer communication register,
the PVC control register, the printer control block register set, the PVC interrupt event
register, and the printer communication interrupt event register.
10.1.1 Printer Communication Register
The printer communication register (PCOMR) contains several bits and fields that control
the status of data transfers to or from the print engine.
Figure 10-1. Printer Communication Register
The core uses the printer command field (write-only) to send an 8-bit command to the print
engine and the printer status field (read-only) receives an 8-bit serial command. The 12-bit
CCLK divisor field determines the period of the clock supplied to the print engine. CCLK
period = CLK1 period
× (CCLK Divisor + 1) × 16. At 16MHz, this provides a range of 1s to
4.1ms per CCLK period.
The PCOMR has three bits that determine the various modes of operation—the CMD/STS
bidirectional (CSB) bit, the SCLK source (SRC) bit, and the CCLK source (CRC) bit. The
CSB bit indicates whether CMD/STS is bidirectional (CSB=1) or output only (CSB=0). The
values programmed in the SRC and CRC bits determine whether the MC68322 (SRC,
CRC=1) or the print engine (SRC, CRC=0) have supplied status or command clocks,
respectively.
= RESERVED
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9
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65432
1
0
15
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65432
1
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PRINTER COMMAND
00FFF500
00FFF502
00FFF504
PRINTER STATUS
CCLK DIVISOR
CSB SRC CRC
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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