ST STM32L4+ Series Reference Manual page 948

DSI Host (DSIHOST) applied to STM32L4R9xx and STM32L4S9xx only
30.9 Functional description: transmission of commands
30.9.1 Transmission of commands in Video mode
The DSI Host supports the transmission of commands, both in High-Speed and Low-Power,
while in Video mode. The DSI Host uses Blanking or Low-Power (BLLP) periods to transmit
commands inserted through the APB Generic interface. Those periods correspond to the
gray areas of
Commands are transmitted in the blanking periods after the following packets/states:
•
Vertical Sync Start (VSS) packets, if the Video Sync pulses are not enabled
•
Horizontal Sync End (HSE) packets, in the VSA, VBP, and VFP regions
•
Horizontal Sync Start (HSS) packets, if the Video Sync pulses are not enabled in the
VSA, VBP, and VFP regions
•
Horizontal Active (HACT) state
Besides the areas corresponding to BLLP, large commands can also be sent during the last
line of a frame. In that case, the line time for the Video mode is violated and the edpihalt
signal is set to request the DPI video timing signals to remain inactive. Only if a command
does not fit into any BLLP area, it is postponed to the last line, causing the violation of the
line time for the Video mode, as illustrated in
948/2301
Figure 219.
Figure 219. Command transmission periods within the image area
VSS
or
HSS
HSS+HBP
HSS
BLLP
BLLP in
RGB burst
mode
BLLP
Figure 220.
RM0432 Rev 6
VSA and
VBP lines
HFP VACT lines
VFP lines
RM0432
MSv35869V1