4 Internal Interfaces

Describes interfaces integrated within the device.

4.1 Power Output

ED-CM4NANO integrates a 2-pin wire-to-board connector (silkscreen marking: J10) delivering 5V/1A output.

4.2 Type-C USB

ED-CM4NANO integrates an internal Type-C USB interface (silkscreen marking: J75) for USB 3.0 expansion.

ED-CM4NANO features an internal RTC battery holder supporting CR1220 coin cell installation, which maintains an uninterrupted real-time clock during power cycles. The RTC clock chip resides on i2c-0 bus at address 0x51.

TIP

CR1220 batteries are excluded in some shipments due to international logistics restrictions. Install a CR1220 coin cell before using RTC functionality.

4.4 Buzzer

ED-CM4NANO incorporates an internal buzzer controlled by GPIO6:

Active-high: Enabled
Active-low: Disabled

4.5 HDMI FPC

ED-CM4NANO contains an FPC HDMI connector (silkscreen: J13) with reserved USB 2.0 touchscreen signals and PWM brightness control signals, supporting LCD display expansion.

Pin	definition	Pin	definition
1	NC	21	GND
2	NC	22	HDMI1_CLKP
3	NC	23	HDMI1_CLKN
4	NC	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

The BACKLIGHT_PWM and LCD_PWR_EN signals correspond to the following GPIO pins on the CM4:

Signal	CM4 GPIO Name
BACKLIGHT_PWM	GPIO12
LCD_PWR_EN	GPIO16