AWC86A Analog Outputs
The AWC86A includes two Analog Output pins. These
outputs are supported by a 12-bit internal digital to analog
convertor within the Slim-Link Server. Three of the
AM186 Programmable Input/Output lines are used to
support this function.
Digital to Analog Convertor
The Digital to Analog Convertor converts 24-bit serial
data bytes into two analog output signals. The serial data
is transmitted synchronously from the AM186 controller
to the Digital to Analog Convertor. The first 12 bits define
the level at DA0; the remaining 12 bits define the level at
DA1. The maximum output voltage on either analog
output is 4.095 volts, the Least Significant Bit equals 1
millivolt.
The three signals which control the integral Digital to
Analog Convertor are PIO3, PIO26 and PIO29. Serial
data is presented to the digital to analog convertor on
PIO26. The serial data clock is presented by PIO3. PIO3
controls the flow of data within the Digital to Analog
Convertor. PIO3 low permits the serial data to be clocked
into the input shift register. When PIO3 is high data is
transferred from the shift register to the DAC Registers
and updates the DA0 AND DA1 outputs.
AWC86A Analog Input Lines
The Slim-Link® Server is available with 8 Analog Input
pins, AWC86A only. These inputs feed into a common
12-bit Analog to Digital Convertor, ADC. Three of the
Programmable Input/Output lines from the AMD186
support these analog inputs.
Analog to Digital Convertor, ADC
An integral Analog to Digital Convertor converts the
analog inputs to a serial digital data stream. The maximum
sampling rate of the ADC is 16.8 KHz. The ADC provides
12-bit resolution; the least significant bit equals .00122
volts.
The AWC86A multiplexes all eight analog inputs into a
single ADC under the control of the AMD186 controller.
With Programmable Input/Output 2 high the AMD186
controller sends the 4-bit multiplexor address on
Programmable Input/Output 26. When Programmable
Input/Output 2 is low, serial data flows from the ADC to
the AMD186 controller on Programmable Input/Output
26. The synchronizing clock for the data is provided by
the AMD186 on Programmable Input/Output 29.
Analog Channel Selection
As mentioned above, a 4-bit word is issued by the
AMD186 controller to select the analog channel. The
logic table below shows how each channel is addressed.
Selected
Channel
All Off
Ch 0
Ch 1
Ch 2
Ch 3
Ch 4
Ch 5
Ch 6
Ch 7
EN
(bit 3)
0
1
1
1
1
1
1
1
1
D2
(bit 2)
x
0
0
0
0
1
1
1
1
D1
(bit 1)
x
0
0
1
1
0
0
1
1
D0
(bit 0)
x
0
1
0
1
0
1
0
1
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