Figure 9 display the highlighted 9 pin connector J303 on bottom side of SoM_IoT_2V0 printed circuit board. This connector allocate the large-scale integrated circuit R-IN32M3-EC with external I2C and two additional UART signals.
Pin 28 (I2C_SDA1) RP01 For Functional Overviewsee also User’s Manual R18UZ0007EJ1100 chapter 18 I2C BUS (IICB)
Pin 29 (I2C_SCL1) RP00
Pin 30 (UART_RXD0)
Pin 31 (UART_TXD0)
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