Silicon Laboratories UDP C8051F370, User Manual

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C 8 0 5 1 F 3 9 x / F 3 7 x
Rev. 0.2 11
5.5. UART VCP Connection Options
The MCU card features a USB virtual COM port (VCP) UART connection via the USB connector (P2). The VCP
connection uses the CP2102 USB-to-UART bridge chip.
The UART pins on the target MCU either connect to the CP2102 USB-to-UART bridge chip or to the UDP
motherboard. The MCU card has level translators with enable pins that normally route the UART connections to
the on-board USB-to-UART bridge chip. However, the UDP motherboard can drive the enable pins to route the
UART connections to the UDP motherboard instead of the on-board USB-to-UART bridge chip. There are two
enable signals: one with a default pull-down (UART_VCP_EN) and one with a default pull-up (UART_SYS_EN).
When using the UART with either the on-board USB-to-UART bridge or the UDP motherboard, install shorting
blocks on header J14 to connect P0.4 to MCU_TX and P0.5 to MCU_RX.
If desired, install shorting blocks for hardware handshaking on P0.6 and P0.7 on the J14 header. Hardware
handshaking is not required for most applications. Firmware must implement hardware handshaking on the target
MCU using P0.6 and P0.7.
5.6. Potentiometer (R36)
The potentiometer is available on P0.7 when a shorting block is placed on J13. To enable the potentiometer, place
a shorting block on J12 to connect the top terminal of the potentiometer to VDD2.
5.7. Screw Terminal (TB1)
The MCU card includes a 5-position screw terminal connection capable of accepting large wires in the field. P0.6,
P0.1/IDAC0, P0.2/IDAC1, ground, and P0.0/VREF are available.
Before the VREF output can be observed on TB1, place a shorting block on J9 which connects P0.0/VREF to
4.7 µF and 0.1 µF decoupling capacitors.
Before the IDAC0 output can be observed on TB1 with an oscilliscope, place a shorting block on J10 which
connects P0.1/IDAC0 to a 1 k

resistor to ground.
Before the IDAC1 output can be observed on TB1 with an oscilliscope, place a shorting block on J11 which
connects P1.2/IDAC1 to a 1 k

resistor to ground.
5.8. Port Pin Headers (J3-J5)
All of the MCU port pins are available on the 0.100 inch headers.
Shorting blocks are placed on J6 and J7, connecting pins P0.2 and P0.3 to the P0.2 and P0.3 headers on J3. Pin
P0.2 and P0.3 can also connect to an external oscillator circuit. When using an external oscillator driver circuit,
remove the shorting block on J6 and J7.