Nuvoton NuMaker-M251SD User manual

NuMaker-M251SD
Aug. 18, 2020 Page 1of 45 Rev 1.00
NUMAKER-M251SD USER MANUAL
Maker Nu-mbed NUC472 User Manual
ARM®Cortex®-M
32-bit Microcontroller
NuMaker-M251SD
User Manual
NuMicro®M251 Series
The information described in this document is the exclusive intellectual property of
Nuvoton Technology Corporation and shall not be reproduced without permission from Nuvoton.
Nuvoton is providing this document only for reference purposes of NuMicro microcontroller based system
design. Nuvoton assumes no responsibility for errors or omissions.
All data and specifications are subject to change without notice.
For additional information or questions, please contact: Nuvoton Technology Corporation.
www.nuvoton.com

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Table of Contents
1Overview.............................................................................................7
2Features .............................................................................................8
3NuMaker-M251SD Overview.....................................................................9
Front View............................................................................................... 9
Rear View..............................................................................................10
Extension Connectors................................................................................11
3.3.1 Pin Assignment for Extension Connectors................................................................ 11
3.3.2 Arduino UNO Compatible Extension Connectors ....................................................... 14
System Configuration ................................................................................16
3.4.1 VIN Power Source............................................................................................ 16
3.4.2 5 V Power Sources ........................................................................................... 16
3.4.3 3.3 V Power Sources......................................................................................... 16
3.4.4 1.8V Power Sources ......................................................................................... 17
3.4.5 Power Connectors............................................................................................ 17
3.4.6 USB Connectors .............................................................................................. 17
3.4.7 Power Switches............................................................................................... 17
3.4.8 Power Supply Models........................................................................................ 18
External Reference Voltage Connector ...........................................................21
Voltage Adjustable Interface(VAI) Connector ....................................................21
Ammeter Connector..................................................................................21
Extension Connectors................................................................................22
Push-Buttons ..........................................................................................22
LEDs....................................................................................................22
Nu-Link2-Me...........................................................................................23
3.11.1 VCOM Switches............................................................................................... 23
3.11.2 Status LEDs ................................................................................................... 23
Toolchains Supporting ...............................................................................24
Nuvoton Nu-Link Driver Installation................................................................24
BSP Firmware Download............................................................................26
Hardware Setup.......................................................................................26
Find the Example Project............................................................................28
Execute the Project under Toolchains.............................................................28
3.17.1 Keil MDK ....................................................................................................... 28

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3.17.2 IAR EWARM................................................................................................... 32
3.17.3 NuEclipse ...................................................................................................... 33
4NuMaker-M251SD Schematics................................................................ 40
Nu-Link2-Me...........................................................................................40
M251 platform.........................................................................................41
Extension Connector.................................................................................42
PCB Placement .......................................................................................43
5REVISION HISTORY............................................................................ 44

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List of Figures
Figure 1-1 NuMaker-M251SD Board ............................................................................................... 7
Figure 3-1 Front View of NuMaker-M251SD.................................................................................... 9
Figure 3-2 Rear View of NuMaker-M251SD.................................................................................. 10
Figure 3-3 M251SD2AE Extension Connectors............................................................................. 11
Figure 3-4 Arduino UNO Compatible Extension Connectors......................................................... 14
Figure 3-5 External Power Supply Sources on Nu-Link2-Me........................................................ 18
Figure 3-6 External Power Supply Sources on M251 platform...................................................... 19
Figure 3-7 Separate the Nu-Link2-Me from NuMaker-M251SD .................................................... 20
Figure 3-8 Wiring between Ammeter Connector and Ammeter..................................................... 21
Figure 3-9 Nu-Link USB Driver Installation Setup.......................................................................... 24
Figure 3-10 Nu-Link USB Driver Installation.................................................................................. 25
Figure 3-11 Open VCOM Function ................................................................................................ 26
Figure 3-12 ICE USB Connector.................................................................................................... 26
Figure 3-13 Device Manger............................................................................................................ 27
Figure 3-14 PuTTY Session Setting .............................................................................................. 27
Figure 3-15 Template Project Folder Path..................................................................................... 28
Figure 3-16 Warning Message of “Device not found” .................................................................... 28
Figure 3-17 Project File Migrate to Version 5 Format.................................................................... 29
Figure 3-18 Debugger Setting in Options Window......................................................................... 29
Figure 3-19 Programming Setting in Options Window................................................................... 30
Figure 3-20 Compile and Download the Project............................................................................ 30
Figure 3-21 Keil MDK Debug Mode............................................................................................... 31
Figure 3-22 Debug Message on Serial Port Terminal Windows.................................................... 31
Figure 3-23 IAR EWARM Window................................................................................................. 32
Figure 3-24 Compile and Download the Project............................................................................ 32
Figure 3-25 IAR EWARM Debug Mode ......................................................................................... 33
Figure 3-26 Debug Message on Serial Port Terminal Windows.................................................... 33
Figure 3-27 Import the Project in NuEclipse .................................................................................. 34
Figure 3-28 Import Projects Windows............................................................................................ 34
Figure 3-29 Open Project Properties Window ............................................................................... 35
Figure 3-30 Project Properties Settings......................................................................................... 35
Figure 3-31 Build Project................................................................................................................ 36
Figure 3-32 Open Debug Configuration......................................................................................... 36
Figure 3-33 Main Tab Configuration .............................................................................................. 37
Figure 3-34 Debugger Tab Configuration ...................................................................................... 37
Figure 3-35 Startup Tab Configuration .......................................................................................... 38

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Figure 3-36 NuEclipse Debug Mode.............................................................................................. 39
Figure 3-37 Debug Message on Serial Port Terminal Windows.................................................... 39
Figure 4-1 Nu-Link2-Me Circuit...................................................................................................... 40
Figure 4-2 M251 platform Circuit.................................................................................................... 41
Figure 4-3 Extension Connectors Circuit ....................................................................................... 42
Figure 4-4 Front Placement ........................................................................................................... 43
Figure 4-5 Rear Placement............................................................................................................ 43

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List of Tables
Table 3-1 Extension Connectors.................................................................................................... 11
Table 3-2 M251SD2AE Full-pin Extension Connectors and GPIO Function List .......................... 13
Table 3-3 Arduino UNO Extension Connectors and M251SD2AE Mapping GPIO List................. 15
Table 3-4 Vin Power Source.......................................................................................................... 16
Table 3-5 5V Power Sources......................................................................................................... 16
Table 3-6 3.3 V Power Sources..................................................................................................... 16
Table 3-7 1.8V Power Sources...................................................................................................... 17
Table 3-8 Power Connectors ......................................................................................................... 17
Table 3-9 USB Connectors ............................................................................................................ 17
Table 3-10 Power Switches ........................................................................................................... 17
Table 3-11 Supply External Power through Nu-Link2-Me ............................................................. 18
Table 3-12 Supply External Power for M251 platform................................................................... 20
Table 3-13 External Reference Voltage Connector....................................................................... 21
Table 3-14 Voltage Adjustable Interface Connector...................................................................... 21
Table 3-15 Ammeter Connector..................................................................................................... 21
Table 3-16 Extension Connectors.................................................................................................. 22
Table 3-17 Push-Buttons ............................................................................................................... 22
Table 3-18 LEDs ............................................................................................................................ 22
Table 3-20 VCOM Function of Nu-Link2-Me.................................................................................. 23
Table 3-21 Operation Status LED Patterns ................................................................................... 23

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1 OVERVIEW
The NuMaker-M251SD is a development board for Nuvoton NuMicro®M251 microcontrollers. The
NuMaker-M251SD consists of two parts: a M251 platform and an on-board Nu-Link2-Me debugger
and programmer. The NuMaker-M251SD is designed for project evaluation, prototype development
and validation with power consumption monitoring function.
The M251 platform is based on NuMicro®M251SD2AE. For the development flexibility, the M251
platform provides the extension connectors of M251SD2AE, the Arduino UNO compatible headers
and able to adopt multiple power supply. Furthermore, the Nuvoton-designed ammeter connector can
measure the power consumption instantly, which is essential for the prototype evaluation.
In addition to the M251 platform, there is an attached on-board debugger and programmer “Nu-Link2-
Me”. The Nu-Link2-Me supports on-chip debugging, online and offline ICP programming via SWD
interface. The Nu-Link2-Me supports virtual COM (VCOM) port for printing debug messages on PC.
Besides, the programming status could be shown on the built-in LEDs. Lastly, the Nu-Link2-Me could
be detached from the development board and becoming a stand-alone mass production programmer.
Figure 1-1 NuMaker-M251SD Board

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2 FEATURES
NuMicro®M251SD2AE microcontroller with function compatible with:
M251SD2AE
M251SC2AE
M251LD2AE
M251LC2AE
M251ZD2AE
M251SD2AE extension connectors
Arduino UNO compatible extension connectors
Ammeter connector for measuring the microcontroller’s power consumption
Fixable board power supply:
External VDD power connector
Arduino UNO compatible extension connector Vin
USB PWR connector on M251 platform
ICE USB connector on Nu-Link2-Me
On-board Nu-Link2-Me debugger and programmer:
Debug through SWD interface
On-line/off-line programming
Virtual COM port function

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3 NUMAKER-M251SD OVERVIEW
Front View
Figure 3-1 Front View of NuMaker-M251SD
Figure 3-1 shows the main components and connectors from the front side of NuMaker-M251SD. The
following lists components and connectors from the front view:
Target Chip: M251SD2AE(U1)
USB PWR Connector(J2)
Arduino UNO Compatible Extension Connectors (NU1, NU2, NU3, NU4)
M251 Extension Connectors (JP3, JP4, JP5 and JP6)
External VDD Power Connector(JP1)
External VSS Power Connector(JP2)
External VREF Connector(VREF1)
VDD Switch(SW2)
Ammeter Connector(AMMETER)
Reset Button(SW1)
Power LED and PB14 LED(LEDG1 and LEDR1)
Nu-Link2-Me
VCOM Switch
ICE Chip: M48SSIDAE(ICEU2)
ICE USB Connector(ICEJ3)
ICE Status LED(ICES0,ICES1, ICES2, ICES3)
Off-line Program Button(ICESW1)

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Rear View
Figure 3-2 shows the main components and connectors from the rear side of NuMaker-M251SD.
The following lists components and connectors from the rear view:
Nu-Link2-Me
MCUVCC Power Switch (ICEJPR1)
ICEVCC Power Switch (ICEJPR2)
ICEVCC Power Switch
MCUVCC Power
Switch
Figure 3-2 Rear View of NuMaker-M251SD

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Extension Connectors
Table 3-1 presents the extension connectors.
Connector
Description
JP3, JP4, JP5 and JP6
Full pins extension connectors on the NuMaker-M251SD.
NU1, NU2, NU3 and NU4
Arduino UNO compatible pins on the NuMaker-M251SD.
Table 3-1 Extension Connectors
3.3.1 Pin Assignment for Extension Connectors
The NuMaker-M251SD provides the M251SD2AE target chip onboard and full pins extension
connectors (JP3, JP4, JP5 and JP6). The Figure 3-3 shows the M251SD2AE extension connectors.
JP3
Pin1 ~ Pin16
JP6
Pin49 ~ Pin64
JP5 Pin17 ~ Pin32
JP4 Pin33 ~ Pin48
Figure 3-3 M251SD2AE Extension Connectors

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Header
M251SD2AE
Pin No.
Function
JP3
JP3.1
JP3.2
1
PB.6/EADC0_CH6/USCI1_DAT1/UART1_RXD/BPWM1_CH5/PWM1_BRAKE1
/PWM1_CH5/INT4/ACMP1_O
JP3.3
JP3.4
2
PB.5/EADC0_CH5/ACMP1_N/I2C0_SCL/USCI_CTL0/SC0_CLK/PWM0_CH0/UART2_T
XD/TM0/INT0
JP3.5
JP3.6
3
PB.4/EADC0_CH4/ACMP1_P1/I2C0_SDA/USCI1_CTL1/SC0_DAT/PWM0_CH1/UART2_
RXD/TM1/INT1
JP3.7
JP3.8
4
PB.3/EADC0_CH3/ACMP0_N/I2C1_SCL/UART1_TXD/USCI1_DAT1/SC0_RST/PWM0_
CH2/PWM0_BRAKE0/TM2/INT2
JP3.9
JP3.10
5
PB.2/EADC0_CH2/ACMP0_P1/I2C1_SDA/UART1_RXD/USCI1_DAT0/SC0_PWR/PWM0
_CH3/TM3/INT3
JP3.11
JP3.12
6
PB.1/EADC0_CH1/UART2_TXD/USCI1_CLK/I2C1_SCL/PWM0_CH4/PWM1_CH4/PWM
0_BRAKE0
JP3.13
JP3.14
7
PB.0/EADC0_CH0/UART2_RXD/SPI0_I2SMCLK/I2C1_SDA/PWM0_CH5/QSPI0_MOSI1
/PWM0_CH5/PWM1_CH5/PWM0_BRAKE1
JP3.15
JP3.16
8
PA.11/ACMP0_P0/USCI0_CLK/BPWM0_CH0/TM0_EXT
JP3.17
JP3.18
9
PA.10/ACMP1_P0/USCI0_DAT0/BPWM0_CH1/TM1_EXT
JP3.19
JP3.20
10
PA.9/USCI0_DAT1/UART1_TXD/BPWM0_CH2/TM2_EXT
JP3.21
JP3.22
11
PA.8/USCI0_CTL1/UART1_RXD/BPWM0_CH3/TM3_EXT/INT4
JP3.23
JP3.24
12
PF.6/SC0_CLK/SPI0_MOSI/TAMPER0
JP3.25
JP3.26
13
PF.14/PWM1_BRAKE0/PWM0_BRAKE0/PSIO0_CH3/PWM0_CH4/CLKO/TM3/INT5
JP3.27
JP3.28
14
PF.5/UART2_RXD/UART2_nCTS/PWM0_CH0/BPWM0_CH4/X32_IN/EADC0_ST
JP3.29
JP3.30
15
PF.4/UART2_TXD/UART2_nRTS/PWM0_CH1/BPWM0_CH5/X32_OUT
JP3.31
JP3.32
16
PF.3/UART0_TXD/I2C0_SCL/XT1_IN
JP5
JP5.1
JP5.2
17
PF.2/UART0_RXD/I2C0_SDA/QSPI0_CLK/XT1_OUT/BPWM1_CH1
JP5.3
JP5.4
18
PC.7/UART0_nCTS/I2C1_SMBAL/PWM1_CH2/BPWM1_CH0/TM0/INT3
JP5.5
JP5.6
19
PC.6/UART0_nRTS/I2C1_SMBSUS/PWM1_CH3/BPWM1_CH1/TM1/INT2
JP5.7
JP5.8
20
PA.7/UART0_TXD/I2C1_SCL/PWM1_CH4/BPWM1_CH2/ACMP0_WLAT/TM2/INT1
JP5.9
JP5.10
21
PA.6/UART0_RXD/I2C1_SDA/PWM1_CH5/BPWM1_CH3/ACMP1_WLAT/TM3/INT0
JP5.11
JP5.12
22
VSS
JP5.13
JP5.14
23
VDD
JP5.15
JP5.16
24
PD.15/PWM0_CH5/TM3/INT1
JP5.17
JP5.18
25
PA.5/QSPI0_MISO1/UART0_nCTS/UART0_TXD/I2C0_SCL/BPWM0_CH5/PWM0_CH0
JP5.19
JP5.20
26
PA.4/QSPI0_MOSI1/SPI0_I2SMCLK/SC0_nCD/UART0_nRTS/UART0_RXD/I2C0_SDA/
BPWM0_CH4/PWM0_CH1
JP5.21
JP5.22
27
PA.3/QSPI0_SS/SPI0_SS/SC0_PWR/I2C0_SMBAL/UART1_TXD/I2C1_SCL/BPWM0_C
H3/PWM0_CH2/CLKO/PWM1_BRAKE1
JP5.23
JP5.24
28
PA.2/QSPI0_CLK/SPI0_CLK/SC0_RST/I2C0_SMBSUS/UART1_RXD/I2C1_SDA/BPWM
0_CH2/PWM0_CH3
JP5.25
JP5.26
29
PA.1/QSPI0_MISO0/SPI0_MISO/SC0_DAT/UART0_TXD/UART1_nCTS/BPWM0_CH1/P
WM0_CH4
JP5.27
JP5.28
30
PA.0/QSPI0_MOSI0/SPI0_MOSI/SC0_CLK/UART0_RXD/UART1_nRTS/BPWM0_CH0/P
WM0_CH5
JP5.29
JP5.30
31
VDDIO
JP5.31
JP5.32
32
nRESET
JP4
JP4.1
JP4.2
33
PF.0/UART1_TXD/I2C1_SCL/UART0_TXD/BPWM1_CH0/ICE_DAT
JP4.3
JP4.4
34
PF.1/UART1_RXD/I2C1_SDA/UART0_RXD/BPWM1_CH1/ICE_CLK

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JP4.5
JP4.6
35
PC.5/QSPI0_MISO1/UART2_TXD/I2C1_SCL/PWM1_CH0/PSIO0_CH0
JP4.7
JP4.8
36
PC.4/QSPI0_MOSI1/UART2_RXD/I2C1_SDA/PWM1_CH1/PSIO0_CH1
JP4.9
JP4.10
37
PC.3/QSPI0_SS/UART2_nRTS/I2C0_SMBAL/PWM1_CH2/PSIO0_CH2
JP4.11
JP4.12
38
PC.2/QSPI0_CLK/UART2_nCTS/I2C0_SMBSUS/PWM1_CH3/PSIO0_CH3
JP4.13
JP4.14
39
PC.1/QSPI0_MISO0/UART2_TXD/I2C0_SCL/PWM1_CH4/ACMP0_O
JP4.15
JP4.16
40
PC.0/QSPI0_MOSI0/UART2_RXD/I2C0_SDA/PWM1_CH5/ACMP1_O
JP4.17
JP4.18
41
PD.3/USCI0_CTL1/SPI0_SS/USCI1_CTL0/UART0_TXD
JP4.19
JP4.20
42
PD.2/USCI0_DAT1/SPI0_CLK/UART0_RXD
JP4.21
JP4.22
43
PD.1/USCI0_DAT0/SPI0_MISO
JP4.23
JP4.24
44
PD.0/USCI0_CLK/SPI0_MOSI/TM2
JP4.25
JP4.26
45
PA.12/I2C1_SCL/BPWM1_CH2
JP4.27
JP4.28
46
PA.13/I2C1_SDA/BPWM1_CH3
JP4.29
JP4.30
47
PA.14/UART0_TXD/BPWM1_CH4
JP4.15
JP4.32
48
PA.15/UART0_RXD/BPWM1_CH5
JP6
JP6.1
JP6.2
49
VSS
JP6.3
JP6.4
50
LDO_CAP
JP6.5
JP6.6
51
VDD
JP6.7
JP6.8
52
PC.14/SPI0_I2SMCLK/USCI0_CTL0/QSPI0_CLKTM1
JP6.9
JP6.10
53
PB.15/EADC0_CH15/SPI0_SS/USCI0_CTL1/UART0_nCTS/PSIO0_CH0/PWM1_CH0/T
M0_EXT/PWM0_BRAKE1
JP6.11
JP6.12
54
PB.14/EADC0_CH14/SPI0_CLK/USCI0_DAT1/UART0_nRTS/PSIO0_CH1/PWM1_CH1/
TM1_EXT/CLKO
JP6.13
JP6.14
55
PB.13/EADC0_CH13/ACMP0_P3/ACMP1_P3/SPI0_MISO/USCI0_DAT0/UART0_TXD/P
SIO0_CH2/PWM1_CH2/TM2_EXT
JP6.15
JP6.16
56
PB.12/EADC0_CH12/ACMP0_P2/ACMP1_P2/SPI0_MOSI/USCI0_CLK/UART0_RXD/PS
IO0_CH3/PWM1_CH3/TM3_EXT
JP6.17
JP6.18
57
AVDD
JP6.19
JP6.20
58
VREF
JP6.21
JP6.22
59
AVSS
JP6.23
JP6.24
60
PB.11/EADC0_CH11/UART0_nCTS/I2C1_SCL/SPI0_I2SMCLK/BPWM1_CH0
JP6.25
JP6.26
61
PB.10/EADC0_CH10/USCI1_CTL0/UART0_nRTS/I2C1_SDA/BPWM1_CH1
JP6.27
JP6.28
62
PB.9/EADC0_CH9/USCI1_CTL1/UART0_TXD/UART1_nCTS/I2C1_SMBAL/BPWM1_CH
2
JP6.29
JP6.30
63
PB.8/EADC0_CH8/USCI1_CLK/UART0_RXD/UART1_nRTS/I2C1_SMBSUS/BPWM1_C
H3
JP6.15
JP6.32
64
PB.7/EADC0_CH7/USCI1_DAT0/UART1_TXD/PWM1_BRAKE0/PWM1_CH4/INT5/ACM
P0_O/BPWM1_CH4
Table 3-2 M251SD2AE Full-pin Extension Connectors and GPIO Function List

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3.3.2 Arduino UNO Compatible Extension Connectors
Figure 3-4 shows the Arduino UNO compatible extension connectors.
MISO CLK RESET SS
PA.9 PA.11 nRESET PA.8
USCI0_DAT1 USCI0_CLK
5V MOSI GND -
VDD PA.10 VSS PB.15
USCI0_DAT0
PWM0_CH0 PA.5 D8
PWM0_CH1 PA.4 D9
SPI0_SS PWM0_CH2 PA.3 D10
SPI0_MOSI PWM0_CH5 PA.0 D11
SPI0_MISO PWM0_CH4 PA.1 D12
SPI0_CLK PWM0_CH3 PA.2 D13
VSS VSS
VREF VREF
I2C0_SDA PC.0 SDA
I2C0_SCL PC.1 SCL
UART1_RXD PWM0_CH3 PB.2 D0
UART1_TXD PWM0_CH2 PB.3 D1
I2C1_SDA PWM1_CH1 PC.4 D2
I2C1_SCL PWM1_CH0 PC.5 D3
PWM1_CH2 PC.3 D4
PWM1_CH3 PC.2 D5
PWM1_CH4 PA.7 D6
PWM1_CH5 PA.6 D7
VIN
VSS
VSS
5V
3V
RST
IOREF VDD
NC
A5 PB.1 EADC0_CH1 I2C1_SCL UART2_TXD
A4 PB.0 EADC0_CH0 I2C1_SDA UART2_RXD
A3 PB.4 EADC0_CH4
A2 PB.5 EADC0_CH5
A1 PB.6 EADC0_CH6
A0 PB.7 EADC0_CH7
Figure 3-4 Arduino UNO Compatible Extension Connectors

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Header
NuMaker-M251SD
Header
NuMaker-M251SD
Compatible to
Arduino UNO
GPIO Pin of M251
Compatible to
Arduino UNO
GPIO Pin of M251
N
U
4
NU3.1
D0
PB.2
N
U
2
NU2.6
A5
PB.1
NU3.2
D1
PB.3
NU2.5
A4
PB.0
NU3.3
D2
PC.4
NU2.4
A3
PB.4
NU3.4
D3
PC.5
NU2.3
A2
PB.5
NU3.5
D4
PC.3
NU2.2
A1
PB.6
NU3.6
D5
PC.2
NU2.1
A0
PB.7
NU3.7
D6
PA.7
N
U
1
NU1.8
VIN
-
NU3.8
D7
PA.6
NU1.7
VSS
N
U
3
NU4.1
D8
PA.5
NU1.6
VSS
NU4.2
D9
PA.4
NU1.5
5V
NU4.3
D10
PA.3
NU1.4
3V
NU4.4
D11
PA.0
NU1.3
RST
nRESET
NU4.5
D12
PA.1
NU1.2
IOREF
VDD
NU4.6
D13
PA.2
NU1.1
NC
-
NU4.7
VSS
VSS
NU4.8
VREF
VREF
NU4.9
SDA
PC.0
NU4.10
SCL
PC.1
Table 3-3 Arduino UNO Extension Connectors and M251SD2AE Mapping GPIO List

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System Configuration
The NuMaker-M251SD is able to adopt multiple power supply. External power source includes NU1
Vin (7 V to 12 V), VDD (depends on target chip operating voltage), and PC through USB connector.
By using switches and voltage regulator, multiple power domains can be created on the NuMaker-
M251KG.
3.4.1 VIN Power Source
Table 3-4 presents the Vin power source.
Connector
Net Name in
Schematic
Comment
NU1 pin8
NU1_VIN
Board external power source, with voltage range from 7
V to 12 V. The voltage regulator UP2 converts the NU1
pin8 input voltage to 5 V and supplies it to NuMaker-
M251SD.
Table 3-4 Vin Power Source
3.4.2 5 V Power Sources
Table 3-5 presents the 5 V power sources.
Connector
Net Name in
Schematic
Comment
ICEJ3
USB_HS_VBUS
ICE USB connector supplies 5 V power from PC to
M251 platform and Nu-Link2-Me.
J2
USB_VBUS
USB connector on NuMaker-M251SD supplies 5 V
power from PC to M251 platform and Nu-Link2-Me.
NU1 pin5
NU1_5VCC
ICEJ3, J2 or NU1 pin8 supplies 5 V power to NU1 pin5.
NU1 pin5 supplies 5 V power to target chip or Arduino
adapter board.
Table 3-5 5V Power Sources
3.4.3 3.3 V Power Sources
Table 3-6 presents the 3.3 V power sources.
Voltage Regulator
5V Source
Comment
ICEUP1
USB_HS_VBUS
ICEUP1 converts USB_HS_VBUS to 3.3 V and supplies
3.3V to M251 platform or ICE chip.
UP1
USB_VBUS
UP1 converts USB_VBUS to 3.3 V and supplies 3.3 V
to M251 platform.
Note: SW2.2(NU1 3VCC) should be switched to ON.
UP1
NU1_5VCC
UP1 converts NU1_5VCC to 3.3 V and supplies 3.3 V to
M251 platform.
Note: SW2.2(NU1 3VCC) should be switched to ON.
Table 3-6 3.3 V Power Sources

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3.4.4 1.8V Power Sources
Table 3-7 presents the 1.8 V power source.
Voltage Regular
5V Source
Comment
ICEUP2
USB_HS_VBUS
ICEUP2 converts USB_HS_VBUS to 1.8V and supplies
1.8V to M251 platform or ICE chip.
Table 3-7 1.8V Power Sources
3.4.5 Power Connectors
Table 3-8 presents the power connectors.
Connector
Comment
JP1
VDD connector on the NuMaker-M251SD
JP2
VSS connector on the NuMaker-M251SD.
Table 3-8 Power Connectors
3.4.6 USB Connectors
Table 3-9 presents the USB connectors.
Connector
Comment
ICEJ3
ICE USB connector on Nu-Link2-Me for power supply, debugging and
programming from PC.
J2
USB PWR connector on NuMaker-M251SD for power supply.
Table 3-9 USB Connectors
3.4.7 Power Switches
Table 3-10 presents the power switches.
Switch
Comment
ICEJPR1
Configures the target chip operating voltage at 1.8 V / 3.3 V / 5 V.
ICEJPR2
Configures the ICE chip operating voltage at 1.8 V / 3.3 V.
SW2
Configures the target chip operating voltage at 3.3 V / 5 V.
Table 3-10 Power Switches

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3.4.8 Power Supply Models
External Power Supply through Nu-Link2-Me to Target Chip
The external power supply source on Nu-Link2-Me is shown in Figure 3-5.
Figure 3-5 External Power Supply Sources on Nu-Link2-Me
To use ICEJ3 as external power supply source with Nu-Link2-Me, please follow the below steps:
1. Solder the resistor on ICEJPR1 (MCUVCC) depends on the target chip operating voltage.
2. Solder the resistor on ICEJPR2 (ICEVCC) depends on the ICE chip operating voltage.
3. Switch the SW2 to OFF.
4. Connect the external power supply to JP1.
Table 3-11 presents all power models when supplies external power through Nu-Link2-Me. The Nu-
Link2-Me external power sources are highlighted in yellow.
Model
Target
Chip
Voltage
ICEJ3
ICEJPR1
(MCUVCC)
Selection [1]
ICEJPR2
(ICEVCC)
Selection [2]
ICE
Chip
Voltage
SW2
Selection
J2
Vin
JP1
1
1.8 V
Connect
to PC
1.8 V
1.8 V
1.8 V
Off
Ignore
Ignore
1.8 V
output
2
3.3 V
Connect
to PC
3.3 V (default)
3.3 V (default)
3.3 V
Off
Ignore
Ignore
3.3 V
output
3
5 V
Connect
to PC
5V
3.3 V (default)
3.3 V
Off
Ignore
Ignore
5 V
output
X: Unused.
Note:
1. 0 Ω should be soldered between ICEJPR1’s MCUVCC and 1.8 V / 3.3 V / 5 V.
2. 0 Ω should be soldered between ICEJPR2’s ICEVCC and 1.8 V / 3.3 V.
Table 3-11 Supply External Power through Nu-Link2-Me

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External Power Supply through M251 platform to Target Chip
The external power supply sources on M251 platform are shown in Figure 3-6.
USB Power Connector
(J2)
NU1 pin8 (Vin)
External VDD Connector
(JP1)
External VSS Connector
(JP2)
Figure 3-6 External Power Supply Sources on M251 platform
To use Vin or J2 as external power supply source, please follow the below steps:
1. Switch the SW2 depends on the target chip operating voltage.
2. Remove the resistor on ICEJPR1 (MCUVCC).
3. Solder the resistor on ICEJPR2 (ICEVCC) depends on the ICE chip operating voltage.
4. Connect the external power supply to Vin or J2.
To use JP1 as external power supply source, please follow the below steps:
1. Switch the SW2 to OFF.
2. Remove the resistor on ICEJPR1 (MCUVCC).
3. Solder the resistor on ICEJPR2 (ICEVCC) depends on the ICE chip operating voltage.
4. Connect ICEJ3 to PC.
5. Connect the external power supply to JP1.
To use Vin or J2 as external power supply source with Nu-Link2-Me separated from NuMaker-
M251SD, please follow the below steps:
1. Switch the SW2 depends on the target chip operating voltage.
2. Separate the Nu-Link2-Me from NuMaker-M251SD.
3. Connect the external power supply to Vin or J2.
To use JP1 as external power supply source with Nu-Link2-Me separated from NuMaker-M251SD,
please follow the below steps:
1. Switch the SW2 to OFF.
2. Separate the Nu-Link2-Me from NuMaker-M251SD.
3. Connect the external power supply to JP1.

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USB Power Connector
(J2)
NU1 pin8 (Vin)
External VDD Connector
(JP1)
External VSS Connector
(JP2) Separate Nu-Link2-Me
"
"
Figure 3-7 Separate the Nu-Link2-Me from NuMaker-M251SD
Table 3-12 presents all power models when supplies external power through M251 platform. The
M251 platform external power sources are highlighted in yellow.
Model
Target Chip
Voltage
Vin [1]
J2
ICEJ3
SW2
Selection
JP1
ICEJPR1
(MCUVCC)
Selection [2]
ICEJPR2
(ICEVCC)
Selection [3]
ICE Chip
Voltage [4]
4
3.3 V
7 V ~ 12 V
Input
X
Ignore
NU1
3VCC
3.3 V output
Remove
resistor
3.3 V
3.3 V
5
3.3 V
X
Connect
to PC
Ignore
NU1
3VCC
3.3 V output
Remove
resistor
3.3 V
3.3 V
6
5 V
7 V ~ 12 V
Input
X
Ignore
NU1
5VCC
5 V output
Remove
resistor
3.3 V
3.3 V
7
5 V
X
Connect
to PC
Ignore
NU1
5VCC
5 V output
Remove
resistor
3.3 V
3.3 V
8
1.8 V ~ 5.5 V
Ignore [5]
Ignore [5]
Connect to
PC
OFF
DC Input
1.8 V ~ 5.5 V
Remove
resistor
1.8 V / 3.3 V
1.8 V / 3.3 V
9
1.8 V ~ 5.5 V
Ignore [5]
Ignore [5]
Nu-Link2-Me
removed
OFF
DC Input
1.8 V ~ 5.5 V
X
X
X
X: Unused.
Note:
1. The Vin input voltage will be converted by voltage regulator UP2 to 5 V.
2. 0Ω should be removed from ICEJPR1’s MCUVCC and 1.8 V / 3.3 V / 5 V.
3. 0Ω should be soldered between ICEJPR2’s ICEVCC and 1.8 V / 3.3 V.
4. The ICE chip voltage should be close to the target chip voltage.
5. JP1 external power input only provides voltage to target chip. Supply external power to Vin or J2 can provide
5V to NU1 pin5 (5V) and 3.3V to NU1 pin4 (3VCC).
Table 3-12 Supply External Power for M251 platform