A/D Converter Signals And Registers - Intel 8XC196NT User Manual

8XC196NT USER'S MANUAL

11.2 A/D CONVERTER SIGNALS AND REGISTERS

Table 11-1 lists the A/D signals and Table 11-2 describes the control and status registers. Al-
though the analog inputs are multiplexed with I/O port pins, no configuration is necessary.
Port Pin A/D Signal
P0.7:4 ACH7:4
— ANGND
— V
REF
Mnemonic Address
AD_COMMAND 1FACH
AD_RESULT 1FAAH, 1FABH
AD_TEST 1FAEH
AD_TIME 1FAFH
INT_MASK 0008H
INT_PEND 0009H
11-2
Table 11-1. A/D Converter Pins
A/D Signal
Type
I Analog inputs. See the "Voltage on Analog Input Pin"
specification in the datasheet.
GND Reference Ground
Must be connected for A/D converter and port operation.
PWR Reference Voltage
Must be connected for A/D converter and port operation.
Table 11-2. A/D Control and Status Registers
A/D Command
This register selects the A/D channel, controls whether the A/D
conversion starts immediately or is triggered by the EPA, and
selects the operating mode.
A/D Result
For an A/D conversion, the high byte contains the eight MSBs from
the conversion, while the low byte contains the two LSBs from a 10-
bit conversion (undefined for an 8-bit conversion), indicates which
A/D channel was used, and indicates whether the channel is idle.
For a threshold-detection, calculate the value for the successive
approximation register and write that value to the high byte of
AD_RESULT. Clear the low byte or leave it in its default state.
A/D Conversion Test
This register enables conversions on ANGND and V
specifies adjustments for zero-offset errors.
A/D Conversion Time
This register defines the sample window time and the conversion
time for each bit.
Interrupt Mask
The AD bit in this register enables or disables the A/D interrupt. Set
the AD bit to enable the interrupt request.
Interrupt Pending
The AD bit in this register, when set, indicates that an A/D interrupt
request is pending.
Description
Description
REF
and