UM0442 datasheet(18/33 Pages) STMICROELECTRONICS

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Hardware configuration and functionality

UM0442

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Figure 15.

S6 selector, this configuration allows RTS functionality

4.16

I2C and BSPI connectors

Both the I2C and BSPI connectors are shared with other devices placed on the board, but

they are useful in order to allow on-system communication capabilities for the STR750-MAP.

The I2C peripheral bus of the microcontroller shares the pin between the 3-axis

accelerometer and the connector for external devices.

Starting from the microcontroller pin out, pins 29 and 30, SDA and SCL respectively, are

connected to the middle points of two 3-pin strip-line selectors, S2 and S1 respectively. If

both these selectors are closed between the middle point and the point 3, we connect the

microcontroller to the I2C bus of the accelerometer sensor. If we close between their middle

point and point 1, the microcontroller is connected to the external I2C connector, allowing

communication with an external device respecting the I2C standard protocol specifications.

The left diagram in Figure 16 shows the configuration to select the accelerometer on the I2C

bus. The diagram on the right is extracted from the schematic.

Table 10.

Pin numbering for the UART connector

Pin number

Function

2Rx1

3Tx1

5GND

7Tx2

8Rx2

9NC

UM0442 Datasheet(PDF) 18 Page - STMicroelectronics