
TXBYTECLKHS
(O)
TXREQUESTHS
(I)
DP/DN
TXREADYHS
(O)
STOPSTATE
(O)
T
HS-PREPARE
T
HS-ZERO
T
LPX
T
HS-TRAIL
T
HS-EXIT
HS DATA transmission
(BYTE1, BYTE2...)
TXDATAHSB7–B0
(I)
VALID DATA
(BYTE2, BYTE3...)
SAMPLED BY DSI_PHY ON +VE
EDGES OF TXBYTECLKHS
BYTE1
DATA HERE IS IGNORED
dss-186
T
HS_SYNC
Public Version
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Display Subsystem Basic Programming Model
Figure 7-141. High-Speed Data Transmission
TXByteClkHS is an output clock which is derived by dividing CLKIN4DDR by 16.
To begin transmission, the protocol drives TXDATAHS with the first byte of data on a rising edge of
TXByteClkHS. It also makes TXREQUESTHS high the same rising edge. The PHY detects
TXREQUESTHS going high on the next rising edge of TXByteClkHS, following which it initiates the LP
Start of Transmission (SoT) procedure.
During a high-speed Data Transmission, these timings are multiple of CLKIN4DDR and programmed by
the following register bit fields:
•
TLPX timing is programmed by the DSS.
[20:16] REG_TLPXBY2 bit field.
•
THS-P THS-ZERO timing is programmed by the DSS.
REG_THSPRPR_THSZERO bit field.
THS-ZERO will be extended, if required, so that the entire LP SoT procedure lasts an integer number of
TXByteClkHS cycles. THS-SYNC corresponds to the length of the sync pattern which is 8 high-speed bits,
and can be configured through the
[31:24] HSSYNCPATTERN bit field.
Towards the end of the SoT procedure, the PHY makes TXREADYHS high on a positive edge of
TXByteClkHS and then start accepting data from TXDATAHS from the next positive edge onwards. The
protocol is expected to provide (new) valid data on TXDATAHS on every positive edge of TXByteClkHS if
TXREADYHS is high.
At the end of the SoT procedure, HS data transmission begins. HS Data Transmission happens LSB first.
To stop data transmission, the protocol drives TXREQUESTHS low on a rising edge of TXByteClkHS. The
PHY detects this change in TXREQUESTHS on the next edge and stops data transmission. TXREADYHS
is made low and data on TXDATAHS, from that point, is ignored.
1761
SWPU177N – December 2009 – Revised November 2010
Display Subsystem
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