ST STM32L4+ Series Reference Manual page 934

DSI Host (DSIHOST) applied to STM32L4R9xx and STM32L4S9xx only
30.6 Functional description: adapted command mode on LTDC
interface
The Adapted Command mode, enables the system to input a stream of pixel from the LTDC
that is conveyed by DSI Host using the Command mode transmission (using the DCS
packets). The Adapted Command mode also supports pixel input control rate signaling and
Tearing Effect report mechanism.
The Adapted Command mode allows to send large amounts of data through the
memory_write_start (WMS) and memory_write_continue (WMC) DCS commands. It helps
in delivering a wider data bandwidth for the memory write operations sent in Command
mode to MIPI
additional commands such as display configuration commands, read back commands, and
tearing effect initialization are to be transferred, then the APB slave generic interface should
be used to complement the Adapted Command mode functionality.
Adapted Command mode of operation supports 16 bpp, 18 bpp, and 24 bpp RGB.
To transmit the image data in Adapted Command mode:
•
Set Command mode (CMDM) bit of the DSI Host mode Configuration Register
(DSI_MCR) to 1.
•
Set DSI mode (DSIM) bit in the DSI Wrapper Configuration Register (DSI_WCFGR) to
1.
To transmit the image data, follow these steps:
•
Define the image area to be refreshed, by using the set_column_address and
set_page_address DCS commands. The image area needs to be defined only once
and remains effective until different values are defined.
•
Define the pixel color coding to be used by using the Color Coding (COLC) field in the
DSI Host LTDC Color Coding Register (DSI_LCOLCR).
•
Define the Virtual Channel ID of the LTDC interface generated packets using the Virtual
Channel ID (VCID) field in the DSI Host LTDC VCID Register (DSI_LVCIDR). These
also need to be defined only once.
•
Start transmitting the data from the LTDC setting the LTDC Enable (LTDCEN) bit of the
DSI_WCR register.
Figure 209
934/2301
®
displays and to refresh large areas of pixels in high resolution displays. If
shows the adapted command mode usage flow.
RM0432 Rev 6
RM0432