DiSEqC Control MT312
11E6
For this example, the DiSEqC™ frequency = --------------- = 22kHz.
4*125
For a 10MHz crystal, the tone frequency range is from 9.8kHz with DISEQC RATIO = 255 to 250kHz with
DISEQC RATIO = 10. A lower value than 10 causes the tone frequency to become unstable, until the DISEQC
RATIO = 0, the default, value giving a 22kHz tone frequency. This range is not guaranteed, the maximum tone
frequency should be used with caution.
5.2.3 DiSEqC™ Instruction (R/W). Register 36 (R/W)
Def
hex
NAME
ADR
B7
B6
B5
B4
B3
B2
B1
B0
DISEQC INSTR
36
DISEQC Instruction [7:0]
R/W
00
Up to eight instruction data bytes are first loaded into a bank of registers through this register. The 2-wire
automatic register address incrementing is turned off during this loading by setting B7: IAI = 1 in RADD,
(register address). The number of bytes (less one) must be defined in the DiSEqC™ instruction register
DISEQC MODE[5:3].
i.e. DISEQC MODE[5:3] = (number of bytes in the DiSEqC™ instruction) - 1
When the DiSEqCTM instruction data bytes have been loaded, set DISEQC MODE[2:0] = 4. At the same time
program DISEQC MODE[5:3] as required. The instruction data is modulated onto the 22kHz signal and output
from the DISEQC[0] pin.
An interrupt is generated 16ms after all the data bytes have been sent and the MT312 then resets DISEQC
MODE[5:0] to zero, see Figure 19 on page 33.
5.2.4 DiSEqC™ 2 Control 1. Registers 121 (R/W)
Def
hex
NAME
ADR
B7
B6
B5
B4
B3
B2
B1
B0
DISEQC2
CTRL1
121
DISEQC2 CTRL1[7:0]
R/W
00
B7-6:
MIN TONE PER
Minimum Tone Period.
B7-6:
MIN TONE PER
00
01
10
11
3.0 * DISEQC RATIO
3.125 * DISEQC RATIO
2.875 * DISEQC RATIO
2.75 * DISEQC RATIO
B7:6
B5:
are for controlling (or fine tuning) the DiSEqC™ 2 receive algorithm.
Send extended pulse to the Status pin 52. This is a test or diagnostics bit. If it is set to 1, then the
cleaned up and extended pulse stream is sent to the status pin so that it can be recorded or observed.
B4:
DiSEqC™ 2 Reset only the DiSEqCTM 2 receive module. Automatically set low again after use.
31
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
