Initialization Procedure
A software reset must be included at the beginning of all programs to initialize the control registers after
power up.
Description: Motorola
Intel Data
RS0 R/W
WR RD b3 b2 b1 b0
1) Read Status Register 1 1 1 0 X X X X
2) Write to Control Register 1 0 0 1 0 0 0 0
3) Write to Control Register 1 0 0 1 0 0 0 0
4) Write to Control Register 1 0 0 1 1 0 0 0
5) Write to Control Register 1 0 0 1 0 0 0 0
6) Read Status Register 1 1 1 0 X X X X
Typical Control Sequence for Burst Mode Applications
Transmit DTMF tones of 50 ms burst/50 ms pause and Receive DTMF Tones.
Sequence:
RS0 R/W
WR RD b3 b2 b1 b0
1) Write to Control Register A 1 0 0 1 1 1 0 1
(tone out, DTMF, IRQ
, Select Control Register B)
2) Write to Control Register B 1 0 0 1 0 0 0 0
(burst mode)
3) Write to Transmit Data Register 0 0 0 1 0 1 1 1
(send a digit 7)
4) Wait for an Interrupt or Poll Status Register
5) Read the Status Register 1 1 1 0 X X X X
-if bit 1 is set, the Tx is ready for the next tone, in which case...
Write to Transmit Register 0 0 0 1 0 1 0 1
(send a digit 5)
-if bit 2 is set, a DTMF tone has been received, in which case....
Read the Receive Data Register 0 1 1 0 X X X X
-if both bits are set...
Read the Receive Data Register 0 1 1 0 X X X X
Write to Transmit Data Register 0 0 0 1 0 1 0 1
NOTE: IN THE TX BURST MODE, STATUS REGISTER BIT 1 WILL NOT BE SET UNTIL 100 ms (2 ms) AFTER THE DATA IS
WRITTEN TO THE TX DATA REGISTER. IN EXTENDED BURST MODE THIS TIME WILL BE DOUBLED TO 200 ms ( 4 ms)
