4 Internal Interface

4.1 SPI Flash

The ED-CM4IND expands a 4MB SPI Flash via SPI for user data storage. The SPI Flash is connected to the CM4's spi-1 bus, with the following pin definitions:

Pin	Signal	CM4 Pinout
1	SPI_CS	GPIO16
2	SPI_SCK	GPIO21
3	SPI_MISO	GPIO19
4	SPI_MOSI	GPIO20

The ED-CM4IND integrates an RTC. For domestically sold versions, a CR1220 coin cell battery (RTC backup power) is pre-installed to ensure a reliable and uninterrupted clock, unaffected by power loss. The RTC clock chip is connected to the i2c-1 bus with a device address of 0x51.

i2c-1 Bus Pin Definition:

Pin	Signal	CM4 Pinout
1	SDA1	GPIO2
2	SCL1	GPIO3

NOTE

Some international logistics do not support battery shipments, so some devices may not include the CR1220 battery. Before using the RTC, ensure a CR1220 coin cell battery is installed on the motherboard.

4.3 Buzzer

The ED-CM4IND integrates a buzzer, controllable via GPIO. The pin definition is as follows:

Pin	Signal	CM4 Pinout
1	BEEP	GPIO25

4.4 MIPI DSI

The ED-CM4IND includes one MIPI DSI interface, labeled "DSI1," supporting LCD screen expansion. The pin definitions are as follows:

	Pin ID	Pin Name
	1	GND
	2	DSI1_D0_N
	3	DSI1_D0_P
	4	GND
	5	DSI1_D1_N
	6	DSI1_D1_P
	7	GND
	8	DSI1_CLK_N
	9	DSI1_CLK_P
	10	GND
	11	SCL0
	12	SDA0
	13	GND
	14	3V3
	15	3V3

4.5 MIPI CSI

The ED-CM4IND includes two MIPI CSI interfaces, labeled "CSI1" and "CSI0," supporting Raspberry Pi Camera expansion.

4.5.1 CSI0

The Pin definition are as follows:

	Pin ID	Pin Name
	1	GND
	2	DSI1_D0_N
	3	DSI1_D0_P
	4	GND
	5	DSI1_D1_N
	6	DSI1_D1_P
	7	GND
	8	DSI1_CLK_N
	9	DSI1_CLK_P
	10	GND
	11	CAM_GPIO
	12	无
	13	ID_SC
	14	ID_SD
	15	3V3

4.5.2 CSI1

The Pin definition are as follows:

	Pin ID	Pin Name
	1	GND
	2	DSI1_D0_N
	3	DSI1_D0_P
	4	GND
	5	DSI1_D1_N
	6	DSI1_D1_P
	7	GND
	8	DSI1_CLK_N
	9	DSI1_CLK_P
	10	GND
	11	CAM_GPIO
	12	NC
	13	SCL0
	14	SDA0
	15	3V3

4.6 FPC HDMI

The ED-CM4IND includes one FPC HDMI interface, labeled "HDMI LCD," with reserved USB 2.0 touch signals and PWM backlight control signals, supporting HDMI touchscreens. A 40-pin 0.5mm pitch FPC cable is recommended for connecting LCD screens.

The Pin definition are as follows:

Pin ID	Pin Name	Pin ID	Pin Name
1	Y+	21	GND
2	X+	22	HDMI1_CLKP
3	Y-	23	HDMI1_CLKN
4	X-	24	GND
5	GND	25	BACKLIGHT_PWM
6	USB_DP	26	GND
7	USB_DM	27	GND
8	GND	28	GND
9	HDMI1_HPD	29	GND
10	HDMI1_SCL	30	GND
11	HDMI1_SDA	31	GND
12	GND	32	LCD_PWR_EN
13	HDMI1_TX2P	33	5V
14	HDMI1_TX2N	34	5V
15	GND	35	5V
16	HDMI1_TX1P	36	5V
17	HDMI1_TX1N	37	5V
18	GND	38	5V
19	HDMI1_TX0P	39	5V
20	HDMI1_TX0N	40	5V

4.7 40-PIN GPIO

The ED-CM4IND includes one 40-pin GPIO header, compatible with Raspberry Pi HAT, supporting various Raspberry Pi expansion accessories. The Pin definitions are as follows:

Pin	Name	IO	Definition	Configured Function
1	3V3	O	3.3V	--
2	5V	I/O	5V	--
3	PIN3	I/O	GPIO2	I2C1_SDA
4	5V	I/O	5V	--
5	PN5	I/O	GPIO3	I2C1_SDL
6	GND	--	GND	--
7	PIN7	I/O	GPIO4	TXD3
8	PIN8	I/O	GPIO14	TXD0
9	GND	--	GND	--
10	PIN10	I/O	GPIO15	RXD0
11	PIN11	I/O	GPIO17	GPIO17
12	PIN12	I/O	GPIO18	BACKLIGHT_PWM
13	PIN13	I/O	GPIO27	GPIO27
14	GND	--	GND	--
15	PIN15	I/O	GPIO22	RELAY
16	PIN16	I/O	GPIO23	LCD_PWR_EN
17	3V3	O	3.3V	--
18	PIN18	I/O	GPIO24	FAN_EN
19	PIN19	I/O	GPIO10	RST_4G
20	GND	--	GND	--
21	PIN21	I/O	GPIO9	RXD4
22	PIN22	I/O	GPIO25	BEEP
23	PIN23	I/O	GPIO11	DIN1
24	PIN24	I/O	GPIO8	TXD4
25	GND	--	GND	--
26	PIN26	I/O	GPIO7	ADC_INT
27	PIN27	I/O	GPIO0	ID_SD
28	PIN28	I/O	GPIO1	ID_SC
29	PIN29	I/O	GPIO5	RXD3
30	GND	--	GND	--
31	PIN31	I/O	GPIO6	USER BUTTON
32	PIN32	GPIO12	TXD5
33	PIN33	I/O	GPIO13	HDMI1_CLKN
34	GND	--	GND	--
35	PIN35	I/O	GPIO19	SPI_MISO
36	PIN36	I/O	GPIO16	SPI_CS
37	PIN37	I/O	GPIO26	DIN2
38	PIN38	I/O	GPIO20	SPI_MOSI
39	GND	--	GND	--
40	PIN40	I/O	GPIO21	SPI_SCK

NOTE

Some GPIO pins on the 40-pin header are pre-configured for onboard functions. Please check before use.

4.8 Mini PCIe Interface

The ED-CM4IND includes one Mini PCIe interface, supporting 4G module expansion (optional). Pin Definitions are as follow:

Pin ID	Pin Name	Pin ID	Pin Name	Pin ID	Pin Name
1	NC	21	GND	41	3V3
2	3V3	22	GPIO10 / PCIE_nRST	42	LED_WWAN
3	NC	23	PCIE_RXN	43	GND
4	GND	24	3V3	44	NC
5	NC	25	PCIE_RXP	45	NC
6	NC	26	GND	46	NC
7	PCIE_CLK_nREQ	27	GND	47	NC
8	USIM_VDD	28	NC	48	NC
9	GND	29	GND	49	NC
10	USIM_DATA	30	NC	50	GND
11	GND	31	PCIE_TXN	51	NC
12	USIM_CLK	32	NC	52	3V3
13	PCIE_CLKP	33	PCIE_TXP	53	GND
14	USIM_RST	34	GND	54	GND
15	GND	35	GND	--	--
16	NC	36	USB_DM	--	--
17	NC	37	GND	--	--
18	GND	38	USB_DP	--	--
19	NC	39	3V3	--	--
20	NC	40	GND	--	--

4G Module Reset Pin Definition:

Pin	Signal	CM4 Pinout
1	RST_4G	GPIO10

4.9 USB 2.0 Pin Header

The ED-CM4IND includes two USB 2.0 pin headers, labeled J44 and J63, with a 4-pin 2.54mm pitch. These can be used to expand USB 2.0 interfaces as needed. Pin Definitions are as follows:

Pin ID	Pin Name
1	5V
2	D-
3	D+
4	GND

4.10 UART Pin Header

The ED-CM4IND includes one UART pin header, labeled J58 and named "UART0." It is a TTL-level serial port with a 4-pin 2.54mm pitch, typically used as a debug serial port. Pin Definitions are as follows:

Pin ID	Pin Name
1	3.3V
2	GND
3	TXD0
4	RXD0

4.11 2-PIN GPIO Pin Header

The ED-CM4IND provides one GPIO via a 2-pin 2.54mm pitch header, labeled J68 and connected to GPIO27 on the CM4. It can be configured for various purposes. Pin definitions are as follows:

Pin ID	Pin Name
1	GND
2	GPIO27

4.12 Micro USB Interface

The ED-CM4IND includes one Micro USB interface, labeled J73 and named "USB PROGRAM," used for eMMC programming. Pin definitions are as follows:

	Pin ID	Pin Name
	1	5V
	2	D-
	3	D+
	4	NC
	5	GND

4.13 5V 1A Output

The ED-CM4IND includes one 5V 1A power output interface, labeled J72, providing 5V 1A DC output for powering external LCD screens. Pin definitions are as follows:

Pin ID	Pin Name
1	5V
2	GND

4.14 PoE Pin Header

The ED-CM4IND includes one PoE pin header for connecting PoE HAT modules. Pin definitions are as follows:

Pin ID	Pin Name
1	VC1-
2	VC1+
3	VC2-
4	VC2+

4.15 Fan Pin Header

The ED-CM4IND includes one fan control interface, labeled J67. Pin definitions are as follows:

Pin ID	Pin Name
1	5V (no pull-up)
2	5V (bring pull)
3	FAN_EN
4	GND
5	GND

TIP

FAN_EN is connected to GPIO24 on the CM4. By controlling GPIO24, the fan can be turned on/off and its speed adjusted.