RADIOMETER TCM3 - Page 72

2.
TCM3
TCM3
and
TCM30
Service
Manual
Main PCB, Continued
(cení dina) Part Function
QD3 | PCO - PC2 | Control output for the Analog PCB input MUX
PC3 655.36 ms clock input
PC4 A/D converter 1 input/Timer T1
PC5 Electrode type coding input
QD3 [TO input | System clock (CLK)
TO output | Audio generator
QD20 (UART):
The programmable UART, functions as a transmitter/receiver and baud rate
generator.
Parallel data from the CPU is converted to serial form by the transmitter, and
appropriate start, stop and parity bits are added to the outgoing serial data.
The incoming data is checked for errors and converted to parallel for transfer to
the CPU. When incoming data is detected, an interrupt will be sent to the CPU
(RSTB).
For further information please refer to Section 6, Input-Output Signals.
The input/output chips QD2, QD3, and QD20 are selected by the decoder QD4.
Display Control The display scanning is controlled by the 0.64 ms clock signal from. The display
multiplex bus ABCD controls the 4-to-16 line decoder QD15 and each scanning
cycle is initiated by a Bus Request (BREQ) signal бот ОБИ pin 8.
During BREQ the address and data buses are released from the CPU, giving the
A0-A3 control to the ABCD bus via the buffer OD14.
The data transfer from OD8 (RAM) to the 7 segments and the display scanning is
synchronised by QD16.
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