Hardware layout and configuration
UM1932
20/31
UM1932 Rev 4
4.14 DSI
LCD
The LCD module is a 4-inch 800x480 TFT color LCD with capacitive touch panel. The LCD
is connected to the MIPI DSI
®
interface of the microcontroller STM32F469NIH6 via the
connector CN10. The DSI (Display Serial Interface) is a specification of the MIPI Alliance
standard and defines the physical interface and the protocol used by the STM32F469NIH6
microcontroller to communicate with such LCD module.
The following ports of the microcontroller STM32F469NIH6 are dedicated to the DSI
interface: DSI_D0_N, DSI_D0_P, DSI_CK_N, DSI_CK_P, DSI_D1_N, DSI_D1_P.
In addition to the DSI dedicated ports, the port PH7 of the microcontroller is used to reset
both the DSI LCD module and the capacitive touchscreen controller.
The port PJ2, connected to the LCD signal TE (Tearing Effect) is an input of the
microcontroller to synchronize the write access from the microcontroller with the LCD scan
refresh, to avoid visible artefacts on the display.
LEDK and LEDA signals of the LCD module are the cathode and anode of the backlight
LEDs.
This backlight requires a power supply voltage of typically 25 V generated from the +5 V by
a switching mode boost converter.
By controlling the EN pin of the converter by a low-frequency PWM signal, it is possible to
switch on/off or to dim the backlight intensity of the LCD module. The control of EN can be
done by software or by hardware:
•
By default, the EN pin of the converter is controlled by the microcontroller software
through DSI commands and CABC signal generated by the LCD module. For such
default configuration the resistor R117 is soldered, R119 is not soldered.
•
The 32F469IDISCOVERY Discovery board offers the option to control the EN pin by
HW through port PA3. In such case, R117 must be removed and R119 soldered.
Table 7. DSI LCD module connector (CN10)
CN10
pin
Signal
name
Description
MCU pins
involved
1
ID
Not connect
-
2
GND
Ground
-
3
CABC
Content Adaptive Brightness Control
-
4
GND
Ground
-
5
RESX
Reset, active low
PH7
6
IOVCC
Digital supply voltage
+3V3
7
GND
Ground
-
8
HSSI_D0_N
MIPI-DSI data lane 0 negative-end I/O
DSI_D0_N
9
NC
Not connect
-
10
HSSI_D0_P
MIPI-DSI data lane 0 positive-end I/O
DSI_D0_P
11
GND
Ground
-
12
HSSI_CLK_N
MIPI-DSI clock lane negative-end input
DSI_CK_N
13
NC
Not connect
-
