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5. CMT2251A-EM
The CMT2251A-EM is the Rx PWM control module with a CMT2251A device, a PWM controlled LED, battery case and a
couple of necessary external components. The EM-Connector on the back side of the module allows the connection to the
USB Programmer. The main components are listed below:
Figure 24. Top View of CMT2251A-EM
1.
EM-Connector
– The EM-Connector is a 10-pin, 2.54 mm male connector used to connect to the USB Programmer.
2.
Power Mode Switch
–The power mode Switch (S1) is used to select the power supply source of the module. The
module can be supplied by the battery (S1 switched to the VBAT side) or the EM-Connector (S1 switched to the VEXT
side). It is recommended to put the switch to the VEXT side when programming the CMT2251A-EM with the USB
Programmer.
3.
LED
– A red LED is available on the PCB connecting the PWM pin of the CMT2251A. An NPN transistor is used to turn
on the LED when there is PWM signal coming out from the CMT2251A to adjust the brightness of the LED.
The definition of the EM-connector on the CMT2251A-EM is given below:
Pin
Signal Name
1
CSB
2
GND
3
NC
4
VDD
5
SCL
6
NC
7
SDA
8
NC
9
NC
10
NC
Figure 25. EM-Connector on the
CMT2251A-EM
Table 13. CMT2251A-EM EM-Connector Pin Definition
