Datasheet

ADC0801, ADC0802
ADC0803, ADC0804, ADC0805
www.ti.com SNOSBI1B –NOVEMBER 2009–REVISED FEBRUARY 2013
The key to decoding circuitry is the DM74LS373, 8-bit D type flip-flop. When the Z-80 acknowledges the
interrupt, the program is vectored to a data input Z-80 subroutine. This subroutine will read a peripheral status
word from the DM74LS373 which contains the logic state of the INTR outputs of all the converters. Each
converter which initiates an interrupt will place a logic "0" in a unique bit position in the status word and the
subroutine will determine the identity of the converter and execute a data read. An identifier word (which
indicates which A/D the data came from) is stored in the next sequential memory location above the location of
the data so the program can keep track of the identity of the data entered.
Figure 64. Flow Chart for Auto-Zero Routine
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