The P4M-400 interfaces with four 6 x 2-pin headers (P1 to P4). Space of each pin is 2 mm.


Pin# Name I/O Description
P1.1 GND - Ground
P1.2 GND - Ground
P1.3 TPTX+ In/Out Ethernet Transmit +
P1.4 TPTX- In/Out Ethernet Transmit -
P1.5 TPRX+ In/Out Ethernet Receive +
P1.6 TPRX- In/Out Ethernet Receive -
P1.7 GND - Ground
P1.8 GND - Ground
P1.9 USB_H_D+ In/Out USB Host Data +
P1.10 USB_H_D- In/Out USB Host Data -
P1.11 USB_D_D+ In/Out USB Device Data +
P1.12 USB_D_D- In/Out USB Device Data -


Pin# Name I/O Description
P2.1 VBUS In USB Device VBUS
P2.2 +3.3V - +3.3V Power Input
P2.3 HT0(1.6) In/Out UIO 1.6 / Hardware Timer/Counter 0
P2.4 HT1(1.7) In/Out UIO 1.7 / Hardware Timer/Counter 1
P2.5 HT2(1.8) In/Out UIO 1.8 / Hardware Timer/Counter 2
P2.6 HT3(1.9) In/Out UIO 1.9 / Hardware Timer/Counter 3
P2.7 UIO(0.14) In/Out UIO 0.14
P2.8 SRO(0.15) In/Out UIO 0.15 / Slave Reset Out
P2.9 ISP# In ISP Input (Active LOW)
P2.10 DTX Out Debug Out (UART)
P2.11 RESET# In Reset Input (Active LOW)
P2.12 VBAT In Battery Input


Pin# Name I/O Description
P3.1 NSS(0.0) In/Out UIO 0.0 / SPI NSS
P3.2 SCK(0.1) In/Out UIO 0.1 / SPI SCK
P3.3 MISO(0.2) In/Out UIO 0.2 / SPI MISO
P3.4 MOSI(0.3) In/Out UIO 0.3 / SPI MOSI
P3.5 U0TX(0.4) In/Out UIO 0.4 / UART0 TX
P3.6 U0RX(0.5) In/Out UIO 0.5 / UART0 RX
P3.7 SCL(0.6) In/Out UIO 0.6 / I2C SCL
P3.8 SDA(0.7) In/Out UIO 0.7 / I2C SDA
P3.9 U0RTS(0.8) In/Out UIO 0.8 / UART0 RTS / UART0 TxDE
P3.10 U0CTS(0.9) In/Out UIO 0.9 / UART0 CTS
P3.11 U1TX(0.10) In/Out UIO 0.10 / UART1 TX
P3.12 U1RX(0.11) In/Out UIO 0.11 / UART1 RX


Pin# Name I/O Description
P4.1 U1RTS(0.12) In/Out UIO 0.12 / UART1 RTS / UART1 TxDE
P4.2 U1CTS(0.13) In/Out UIO 0.13 / UART1 CTS
P4.3 STX(1.10) In/Out UIO 1.10 / Slave TX
P4.4 SRX(1.11) In/Out UIO 1.11 / Slave RX
P4.5 GND - Ground
P4.6 GND - Ground
P4.7 +3.3V - +3.3V Power Input
P4.8 AREF In ADC Reference Input
P4.9 ADC0(1.0) In/Out UIO 1.0 / ADC0
P4.10 ADC1(1.1) In/Out UIO 1.1 / ADC1
P4.11 ADC2(1.2) In/Out UIO 1.2 / ADC2
P4.12 ADC3(1.3) In/Out UIO 1.3 / ADC3


At the bottom center of the module is the user-defined LED. This LED is connected to UIO 0.31 and is set to LED for status display at the factory. It can be set to the user output port if necessary, and when the LOW is output, the LED is turned on.