Z8F3224 ZMOTION Development Kit
UM029501-0321
MCU CURRENT MEASUREMENT
User Manual
10
MCU Current Measurement
The MCU current consumption can be easily measured by removing the shunt on J4 (LP Current) or J9
(NP Current) and connecting an ammeter on the respective positive (+) and negative (
–) header pins.
Operating Voltage Adjustment
The MCU operating voltage can be adjusted from 2.0V to 3.5V by the R33 potentiometer. Turn the
potentiometer clockwise to decrease the voltage. The operating voltage can be measured from the J11
header (labeled VCC_T).
UART Interface
The MCU UART can be connected to the Serial to USB converter (U8) and/or directly available as TTL
signals via J10 (NP MCU) or J5 (LP MCU). Use the jumpers on J17 (NP MCU) and J16 (LP MCU) to
select the desired connection.
Table 5. LP MCU UART Connections
Use caution when using a separate Serial to USB converter cable connected to J10 or J5. The Z8F3224
supply voltage (VCC_T) selected by R33 must match the drive level provided by the cable. The sample
applications provided avoid this issue as follows:
•
Txd: Configured as Open Drain without an internal pull up. The pull up resistor should be
provided on the Rxd (cable) side.
•
Rxd: Internal pull-up resistor connected to VCC_T is enabled. The Txd side (cable side) should
drive using Open Drain.
•
The Serial to USB chip (U8) on the ZMOTIONL400 board is configured in this manner.
•
Failing to follow this precaution can cause unexpected behaviour and inaccurate current
measurement reading through J9 (NP MCU) or J4 (LP MCU).
LP UART
Connection
Txd
(J16)
Rxd
(J16)
J5 Header
7-8
5-6
USB (U8)
3-4
1-2
NP UART
Connection
Txd
(J17)
Rxd
(J17)
J10 Header
7-8
5-6
USB (U8)
3-4
1-2
Table 4. NP MCU UART Connections
