tda9950 NXP Semiconductors, tda9950 Datasheet - Page 8

• Manufacturer Part Number: tda9950
• Description: Tda9950 Cec/i?c-bus Translator
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA9950_1
Product data sheet
8.5 Data register protocol
Table 12.
Table 13.
Table 14.
Communication between the TDA9950 and the host using the CEC Data Registers is
carried out using frames of information. The host is the master of all data transfers; the
TDA9950 uses the INT line to inform the host that it has data available.
Before a frame is read or written, the host must set the REG_PTR field in the Address
Pointer Register to the base CEC Data Register address. Successive reads or writes
automatically increment the REG_PTR as the frame is transferred. Message transfers can
only start from the first CEC Data Register at address 07h and not from higher addresses,
as messages must be transferred complete and not in fragments.
Each frame consists of a byte count, a service selector and then zero or more (up to 17)
parameters as shown in
Bit
7 to 0
Bit
7 to 5
4
3
2 to 0
Bit
7 to 0
Fig 3. Frame format for the data register protocol
Symbol
ACKL[7:0]
Symbol
-
ENABLE_ERROR
-
RETRY[2:0]
Symbol
FrameByteCount/
ServiceSelector/
Parameters[7:0]
ACKL - CEC Address ACK Low register (address 05h) bit description
(Read/Write)
CCONR - CEC Configuration Register (address 06h) bit description (Read/Write)
CDR[0:18] - CEC Data Registers (addresses 07h to 19h) bit description
(Read/Write)
FrameByteCount
Register CDR0
Rev. 01 — 16 November 2007
Figure
3.
Description
CEC Address ACK Low register
For each bit:
0 = messages to the corresponding logical address will not be
acknowledged.
1 = messages to the corresponding logical address are
acknowledged and forwarded to the host.
Description
not used
ENABLE_ERROR:
0 = no specific action.
1 = notify the host of all errors via the TDA9950 Error Register
and via the CECData.err service (see
not used
RETRY[2:0]: retry count to be used by the TDA9950. The
maximum value is 5; values greater than 5 will still give 5
retries.
Description
FrameByteCount/ServiceSelector/Parameters:
Length of message in B, Type of message, 17 B for message
content; see
ServiceSelector
Register CDR1
Section 8.5 “Data register
Register CDR2
[Parameters]
[...]
CEC/I
001aag924
Section
protocol”.
[...]
TDA9950
© NXP B.V. 2007. All rights reserved.
2
C-bus translator
8.5.4).
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