MSK Modem
5
MX809
Pin
Signal
Description
This is the ‘C-BUS’ serial Clock input. This clock, produced by the
21 Serial Clock
microcontroller, is used for transfer timing of commands and data to and from the
MSK Modem. See Section 6 and Section 7.1.4.
22 Address Select
This pin enables two MX809s to be used on the same C-BUS, providing full-
duplex operation. When at a logic “1” Address/Command bytes (with the
exception of a General Reset) must have bit 3 set to a logic “1” to address this
device. See Table 5 and Table 6.
23
24
This input can be used to reactivate the MX809 from Powersave. The device will
be in Powersave when both this pin and bit 2 of the Control Register are set to
logic “1”. Recovery from Powersave is achieved by putting either the Wake pin or
the Powersave bit in the Control Register to logic “0”. This allows MX809
activation by the microcontroller or an external signal, such as R.S.S.I. or Carrier
Detect. See Table 3.
Wake
V
DD
Positive supply. A single +5.0V power supply is required. Levels and voltages
within the MSK Modem are dependent upon this supply.
Table 1: Signal List
TX Idle
RX Data Ready
TX Data Ready
RX Sync Detect
RX SYNC Detect
Interrupt outputs can be disabled by bit 3 of the Control Register
Table 2: IRQ Conditions
Powersave (CR bit 2)
MX809 Condition
Wake
1
0
1
0
1
1
0
0
Powersave
Enabled
Enabled
Enabled
Table 3: Wake and Powersave Conditions
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