Digitally Controlled Analog I/O Processor
4
MX839 PRELIMINARY INFORMATION
2 Signal List
Pin No.
Name
Type
Description
1
output The output of the on-chip oscillator inverter.
XTAL
2
3
XTAL/CLOCK
SERIAL CLOCK
input
input
The input to the on-chip oscillator inverter, for external Xtal circuit or clock.
The 'C-BUS' serial clock input. This clock, produced by the µC, is used for
transfer timing of commands and data to and from the device. See Figure 5.
4
5
COMMAND DATA
REPLY DATA
input
The 'C-BUS' serial data input from the µC. Data is loaded into this device in
8-bit bytes, MSB (B7) first, and LSB (B0) last, synchronized to the SERIAL
CLOCK. See Figure 5.
output The 'C-BUS' serial data output to the µC. The transmission of REPLY DATA
bytes is synchronized to the SERIAL CLOCK under the control of the CS
input.
This tri-state output is held at high impedance when not sending data to the
µC. See Figure 5.
6
7
input
The 'C-BUS' data loading control function. This input is provided by the µC.
Data transfer sequences are initiated, completed or aborted by the CS signal.
See Figure 5.
CS
output This output indicates an interrupt condition to the µC by going to a logic '0'.
This is a 'wire-ORable' output, enabling the connection of up to 8 peripherals
to 1 interrupt port on the µC. This pin has a low impedance pulldown to logic
'0' when active and a high-impedance when inactive. An external pullup
resistor is required.
IRQ
The conditions that cause interrupts are indicated in the IRQ FLAG register
and are effective if not disabled.
8
A/DIN1
A/DIN2
A/DIN3
A/DIN4
input
input
input
input
Analog to digital converter input 1 (A/D1)
Analog to digital converter input 2 (A/D2)
Analog to digital converter input 3 (A/D3)
Analog to digital converter input 4 (A/D4)
9
10
11
12
V
SS
power Negative supply (ground) for both analog and digital supplies.
13
V
BIAS
output An analog bias line for the internal circuitry, held at AV /2. This pin must be
DD
bypassed by a capacitor mounted close to the device pins.
No internal connection. Do not make any connection to this pin.
output Digital to analog converter No. 1 output (DAC1)
output Digital to analog converter No. 2 output (DAC2)
output Digital to analog converter No. 3 output (DAC3)
No internal connection. Do not make any connection to this pin.
14
15
16
17
18
19
N/C
DACOUT1
DACOUT2
DACOUT3
N/C
AV
power Positive analog supply. Analog levels and voltages are dependent upon this
supply. This pin should be bypassed to VSS by a capacitor.
DD
20
21
22
23
24
MOD1 IN
MOD2 IN
MOD1
input
input
Input to MOD1 variable attenuator.
Input to MOD2 variable attenuator.
output Output of MOD1 variable attenuator.
output Output of MOD2 variable attenuator.
MOD2
DV
power Positive digital supply. Digital levels and voltages are dependent upon this
supply. This pin should be bypassed to VSS by a capacitor.
DD
© 1998 MXxCOM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050 Fax: 336 744-5054
Doc. # 20480164.002
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