MT312C ZARLINK [Zarlink Semiconductor Inc], MT312C Datasheet - Page 33

• Manufacturer Part Number: MT312C
• Description: Satellite Channel Decoder
• Manufacturer: ZARLINK [Zarlink Semiconductor Inc]

B[1-0]: MAX TONE PER
5.3 DiSEqC Control Read Registers
5.3.1 DiSEqC™M 2 Interrupt Indicators. Register 118 (R)
Note that the most significant four bits are not reset on read. The least significant four bits are interrupt bits
which are reset when the register is read. Interrupts indicate events in history. The interrupts may be enabled to
drive the IRQ pin 57 by setting required bit(s) in the DISEQC2 CTRL1 register 121, see 31.
B7-4:
B3:
B2:
DISEQC2 INT
NAME
Bits B7-4 denote the following number of bytes received:
Hence this is the number of bytes that would be in the FIFO BUFFER if this buffer had unlimited
capacity. Since the size of this buffer is only 8 bytes, if the above difference, given by bits B7-4,
exceeds eight, that indicates buffer overflow.
Silent period exceeds 176 ms interrupt (reset on read)
The host may enable interrupts B1 and B3. Then when an interrupt is received, the host may read the
DISEQC2 INT register. Then if bit B3 is one and bit B1 is 0, this indicates there has been a
continuous period 176ms of silence since the end of the transmission. If the host is expecting a reply,
then this silence may be taken to signify a hardware fault in the system.
There is a 5-bit number in the DISEQC2 STATUS BYTE which indicates the length of a continuous
period of silence up to the read time, in multiples of 16 ms.
Receive error interrupt (reset on read).
Bit B2 indicates an error in the received message. This does not refer to a parity error. It indicates
that a bit has been lost due to excessive noise or interference in the return channel. This is identified
within MT312 by the occurrence of an excessively long tone or silence period within a byte.
B1-0:
B1-0:
101
110
111
00
01
10
11
ADR
118
B7-4 = (Number of bytes received - Number of bytes read)
Maximum Tone Period.
B7
B6
6.25 * DISEQC RATIO
5.75 * DISEQC RATIO
6.0 * DISEQC RATIO
5.5 * DISEQC RATIO
12 * DISEQC RATIO
13 * DISEQC RATIO
14 * DISEQC RATIO
MAX TONE PER
TONE EXT PER
B5
DISEQC2 INT[7:0]
B4
B3
DiSEqC Control
B2
B1
(default)
(default)
B0
R
MT312
hex
Def
00
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