DHCOM STM32MP1 Linux
Linux virtual machine for development
- Please have a look at: Virtual Machine for Application Development
Linux Kernel
How to build a Kernel
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Get sources from Github
Configure and build the Device Tree + Kernel
Create the FIT-image with our script (Download link)
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Kernel Userspace Interfaces to Access Hardware
RS-485 on picoITX
Control GPIOs
DHCOM Name: alt. DHCOM Name: SO-DIMM Pin# CPU Pad Name GPIO A 154 PF3 GPIO B 156 PD6 GPIO C 162 PG0 GPIO D 163 PD12 GPIO E 164 PC6 GPIO F 165 PD11 GPIO G 167 PI0 GPIO H 173 PI2 GPIO I 175 PI3 GPIO J CIF HSYNC 74 PH8 GPIO K CIF PCLK 72 PA6 GPIO L CIF MCLK 70 PG8 GPIO M CIF VSYNC 68 PI5 GPIO N CIF D9 66 PH7 GPIO O CIF D8 64 PI1 GPIO P CIF D7 62 PE6 GPIO Q CIF D6 60 PB8 GPIO R CIF D5 58 PI4 GPIO S CIF D4 56 PH14 GPIO T CIF D3 54 PH12 GPIO U CIF D2 52 PH11 GPIO V CIF D1 50 PH10 GPIO W CIF D0 48 PH9 INT HIGHEST PRIORITY 151 PI8
- RS-485 device
DHCOM UART 2 /dev/ttySTM2
- Compilation on target
gcc tty_rs485_test_v1.1.c -o tty_rs485_test gcc tty_rs485_flags_v1.0.c -o tty_rs485_flags
- Show UART flags
./tty_rs485_flags /dev/ttySTM2
- Set tty device to raw mode
stty -F /dev/ttySTM2 115200 raw -echo -echoe
- Send data with demo program
echo -n -e "\n\rHallo RS485 Welt!" ¦ ./tty_rs485_test /dev/ttySTM2
- Receive data with demo program
./tty_rs485_test /dev/ttySTM2
- Download example source code
CAN interface
- Setup CAN interface with baudrate 500kbit/sec.
ip link set can0 up type can bitrate 500000
- Start to listen on CAN port
candump can0
- Send test message
cansend can0 100#11.2233.44556677.88
- Deinitialize CAN port
ip link set can0 down
UART Interfaces
DHCOM UART 1 /dev/ttySTM0 DHCOM UART 2 /dev/ttySTM2 DHCOM UART 3 /dev/ttySTM1
I2C Interfaces
DHCOM I2C 1 /dev/i2c-1 DHCOM I2C 2 /dev/i2c-0 On Module Devices /dev/i2c-2
FAQ
USB 1.1 problems: Custom board without USB 2.0 hub inbetween the MP1 USB host port?
And in that case, have a look at arch/arm/boot/dts/stm32mp15xx-dhcom-picoitx.dtsi and how the OHCI (!) is enabled there. And of course, make sure the kernel config options are enabled accordingly (like for the PicoITX machine)
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meta-dhsom-stm32-bsp$ git grep OHCI |
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recipes-kernel/linux/linux-stable/5.10/dh-stm32mp1-common/dh-stm32mp1-dhsom-common.cfg:CONFIG_USB_OHCI_HCD=y |
arch/arm/boot/dts/stm32mp15xx-dhcom-picoitx.dtsi snippet:
&usbh_ehci {
phys = <&usbphyc_port0>;
status = "okay";
};
&usbh_ohci { // <---------------- HERE
phys = <&usbphyc_port0>;
status = "okay";
};
&usbotg_hs {
dr_mode = "otg";
pinctrl-0 = <&usbotg_hs_pins_a>;
pinctrl-names = "default";
phy-names = "usb2-phy";
phys = <&usbphyc_port1 0>;
vbus-supply = <&vbus_otg>;
status = "okay";
};
&usbphyc {
status = "okay";
};
&usbphyc_port0 {
phy-supply = <&vdd_usb>;
vdda1v1-supply = <®11>;
vdda1v8-supply = <®18>;
};
&usbphyc_port1 {
phy-supply = <&vdd_usb>;
vdda1v1-supply = <®11>;
vdda1v8-supply = <®18>;
};
System stability or USB Host problems?
If a display with higher resolution and pixel clock > 48 MHz is used, then this can case USB host and/or system stability problems.
Workaround: The OSPEEDR must be set to OSPEEDR = 1 for LCD_CLK and OSPEEDR = 0 for all other LTDC signals.
&pinctrl {
ltdc_pins_ customhmi: ltdc-dh-1 {
pins1 {
pinmux = <STM32_PINMUX('I', 14, AF14)>; /* LCD_CLK */
bias-disable;
drive-push-pull;
slew-rate = <1>;
};
pins2 {
pinmux = <STM32_PINMUX('I', 12, AF14)>, /* LCD_HSYNC */
<STM32_PINMUX('I', 13, AF14)>, /* LCD_VSYNC */
...
<STM32_PINMUX('K', 6, AF14)>; /* LCD_B7 */
bias-disable;
drive-push-pull;
slew-rate = <0>;
};
};
ltdc_sleep_pins_ customhmi: ltdc-sleep-dh-1 {
pins {
pinmux = <STM32_PINMUX('I', 14, ANALOG)>, /* LCD_CLK */
...
<STM32_PINMUX('K', 6, ANALOG)>; /* LCD_B7 */
};
};
};
USB OTG: Custom board where the USB-OTG port is only used as host?
On the DHCOM standard, the second USB port of the STM32MP1 is usually an USB-OTG port. If you have a custom board where you want to use the USB-OTG port in host mode only, you should consider the following:
The USB-OTG controller on the STM32MP1, DWC2, does support host mode but is rather inefficient (in comparison to a dedicated USB host controller). The following block diagram shows, that it is possible on the STM32MP1 to alter the pinmuxing, so that the USB-OTG port is used with the USB Host controller of the STM32MP1 (instead of using the DWC2 OTG controller):
Host port#1: EHCI/OHCI controller _________ HS PHY port #1 (SoC balls D+/D- #1)
Host port#2: EHCI/OHCI controller __
\
|_____ HS PHY port #2 (SoC balls D+/D- #2)
DWC2 OTG controller_________________/|
|
UTIM switch__________________|
This change can be made in the device tree with disabling the DWC2 controller and adding the second usb_phyc port to the nodes of usbh_ehci and (if applicable) usbh_ohci. These nodes are usually in the .dtsi file of the board (e.g. for the PicoITX: arch/arm/boot/dts/stm32mp15xx-dhcom-picoitx.dtsi). Here a is snippet how this could look like:
&usbh_ehci {
phys = <&usbphyc_port0>, <&usbphyc_port1 1>; // <-------- HERE
status = "okay";
};
&usbh_ohci {
phys = <&usbphyc_port0>, <&usbphyc_port1 1>; // <-------- HERE
status = "okay";
};
&usbotg_hs {
status = "disabled"; // <-------- HERE
};
&usbphyc {
status = "okay";
};
&usbphyc_port0 {
phy-supply = <&vdd_usb>;
vdda1v1-supply = <®11>;
vdda1v8-supply = <®18>;
};
&usbphyc_port1 {
phy-supply = <&vdd_usb>;
vdda1v1-supply = <®11>;
vdda1v8-supply = <®18>;
};
How to try QtWebengine
The QtWebengine is part of the DH default images. Please stop the Weston desktop, before the start of the Browser.
Older images: "systemctl stop weston@root.service" Newer images: "systemctl stop weston.service"
How to start the Browser:
QT_QPA_PLATFORM=eglfs QT_QPA_EGLFS_ALWAYS_SET_MODE=1 QT_QPA_EGLFS_KMS_CONFIG=/etc/default/qt5-eglfs-kms.json qtwebengine-minimal http://YOUR-TEST-PAGE/ --no-sandbox
