ARTERY AT-START-F425 User manual

AT-START-F425 User Manual
2021.10.20 1Rev 1.00
www.arterytek.com
Getting started with AT32F425R8T7-7
Introduction
AT-START-F425 is designed to help you explore the high performance of the 32-bit microcontroller
AT32F425 that embeds ARM Cortex®-M4 core, and expedite application development.
AT-START-F425 is an evaluation board based on AT32F425R8T7-7 microcontroller. The device
contains such peripherals as LEDs, buttons, USB micro-B connector, type-A connector, ArduinoTM
Uno R3 extension interface. This evaluation board embeds AT-Link-EZ for debugging/programming
without the need of other development tools.

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Contents
1Overview................................................................................................................. 5
1.1 Features ...................................................................................................................5
1.2 Definition of terms .................................................................................................... 5
2Quick start .............................................................................................................. 6
2.1 Get started................................................................................................................6
2.2 AT-START-F425 development toolchains ................................................................. 6
3Hardware and layout ............................................................................................. 7
3.1 Power supply selection............................................................................................. 9
3.2 IDD ........................................................................................................................... 9
3.3 Programming and debugging: embedded AT-Link-EZ .............................................. 9
3.4 Boot mode selection...............................................................................................10
3.5 External clock source .............................................................................................10
3.5.1 HEXT clock source.....................................................................................................10
3.5.2 LEXT clock source .....................................................................................................10
3.6 LEDs .......................................................................................................................11
3.7 Buttons ....................................................................................................................11
3.8 USB OTG ................................................................................................................11
3.9 0Ω resistors ............................................................................................................ 12
3.10 Extension interfaces ............................................................................................... 13
3.10.1 ArduinoTM Uno R3 interface.......................................................................................13
3.10.2 LQFP64 I/O extension interface.................................................................................14
4Schematic ............................................................................................................. 15
5Revision history................................................................................................... 19

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List of tables
Table 1. Boot mode selection jumper settings...................................................................................10
Table 2. 0Ωresistor settings ...............................................................................................................12
Table 3. ArduinoTM Uno R3 extension interface pin definition...........................................................13
Table 4. Document revision history....................................................................................................19

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List of figures
Figure 1. Hardware block diagram ......................................................................................................7
Figure 2. Top layer ...............................................................................................................................8
Figure 3. Bottom layer .........................................................................................................................8
Figure 4. Schematic (AT-Link-EZ).....................................................................................................15
Figure 5. Schematic (microcontroller)................................................................................................16
Figure 6. Schematic (power supply and peripherals)........................................................................17
Figure 7. Schematic (extension interfaces).......................................................................................18

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1 Overview
1.1 Features
AT-START-F425 has the following characteristics:
AT-START-F425 has an on-board AT32F425R8T7-7microcontroller that embeds ARM Cortex®-
M4 32-bit core, 64 KB Flash memory and 20 KB SRAM, in LQFP64 7x7mm packages.
On-board AT-Link interface:
−On-board AT-Link-EZ can be used for programming and debugging (AT-Link-EZ is a
simplified version of AT-Link, without offline mode support)
−If AT-Link-EZ were disassembled from the board by bending it along the joint, this interface
can be connected to an independent AT-Link for programming and debugging.
Various power supply methods:
−USB bus of AT-Link-EZ
−USB OTG bus (VBUS) of AT-START-F425
−External 5 V power supply (E5V)
−External 3.3 V power supply
4 x LED indicators:
−LED1 (red) indicates 3.3 V power-on
−3 x USER LEDs, LED2 (red),LED3 (yellow) and LED4 (green), indicate operation status
User button and Reset button
8 MHz HEXT crystal
32.768 kHz LEXT crystal
On-board USB type-A and micro-B connectors in order to demonstrate OTG1 function
Rich extension interfaces are available for quick prototyping
−ArduinoTM Uno R3 extension interface
−LQFP64 I/O extension interface
1.2 Definition of terms
Jumper JPx ON
Jumper is installed.
Jumper JPx OFF
Jumped is not installed.
Resistor Rx ON
Short by solder or 0Ω resistor.
Resistor Rx OFF
Open.

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2 Quick start
2.1 Get started
Configure the AT-START-F425 board in the following sequence:
1. Check the Jumper’s position on board:
JP1 is connected to GND or OFF (BOOT0 = 0, and BOOT0 has an pull-down resistor in the
AT32F425R8T7-7);
JP2 is connected to USART1.
2. Connect AT_Link_EZ to PC via a USB cable (Type A to micro-B), and supply power to the
evaluation board via a USB connector CN6. LED1 (red) is always on, and three other LEDs
(LED2 to LED4) start to blink in turn.
3. After pressing the user button (B2), the blinking frequency of three LEDs are changed.
2.2 AT-START-F425 development toolchains
ARM®Keil®: MDK-ARM™
IAR™: EWARM

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3 Hardware and layout
AT-START-F425 board is designed around an AT32F425R8T7-7 microcontroller in LQFP64 7x7
mm package.
Figure 1 shows the connections between AT-Link-EZ, AT32F425R8T7-7 and their peripherals
(buttons, LEDs, USB OTG, and extension connectors)
Figure 2 and Figure 3 shows their respective locations on the AT-Link-EZ and AT-START-F425
board.
Figure 1. Hardware block diagram
AT32F425R8T7-7
I/O
I/O
I/O
I/O
NRST
Reset
button
User
button
Micro-USB
Arduino extension
interface
Arduino extension
interface
LQFP64 I/O extension interface
LQFP64 I/O extension interface
USB type-A
AT-Link
interface
AT-Link-EZ
User LED
LED2~LED4
Micro-USB

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Figure 2. Top layer
LQFP64 I/O extension interface
Arduino Uno extension interface
AT32F425R8T7-7
Arduino Uno
extension interface
USB Micro-B
connector
Jumper for USART1
and OTG1
Arduino Uno extension interface
LQFP64 I/O extension interface
HSE 8 MHz crystal
User
button
Reset
button
User LED
Jumper
for boot
mode
select
Power LED USART1
interface
AT-Link
interface
AT-Link-EZ
USB Type-A
connector
LEXT 32.768 kHz crystal
Jumper for IDD
measurement
Figure 3. Bottom layer

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3.1 Power supply selection
The AT-START-F425 can not only be provided with 5 V through a USB cable (either through USB
connector CN6 on AT-Link-EZ or USB OTG connector CN5 on AT-START-F425), but also be
provided with an external 5 V power supply (E5V). Then 5 V power provides 3.3 V for the
microcontroller and its peripherals using on-board 3.3 V voltage regulator (U2).
5 V pin of J4 or J7 can also be used as an input power, so the AT-START-F425 board can be
supplied through a 5 V power unit.
The 3.3 V pin of J4, or the VDD of J1 and J2 can be used as 3.3 V input directly, so AT-START-
F425 board can also be supplied by a 3.3 V power unit.
Note: 5 V power supply must be provided through USB connector (CN6) on AT-Link-EZ. Any other
method cannot power the AT-Link-EZ.
When another board is connected to J4, 5 V and 3.3 V can be used output power, J7’s 5V pin as 5
V output power, the VDD pin of J1 and J2 as 3.3 V output power.
3.2 IDD
When JP3 OFF (symbol IDD) and R4 OFF, an ammeter can be connected to measure the power
consumption of AT32F425R8T7-7.
JP3 OFF, R4 ON:
AT32F425R8T7-7 is powered. (Default setting and JP3 plug is not mounted before shipping)
JP3 ON, R4 OFF:
AT32F425R8T7-7 is powered.
JP3 OFF, R4 OFF:
An ammeter must be connected to measure the power consumption of AT32F425R8T7-7. If
there is no ammeter available, the AT32F425R8T7-7 cannot be powered.
3.3 Programming and debugging: embedded AT-Link-EZ
The evaluation board integrates Artery AT-Link-EZ for users to program/debug the
AT32F425R8T7-7 on the AT-START-F425 board. AT-Link-EZ supports SWD interface mode, SWO
debug, and a set of virtual COM ports (VCP) to connect to the USART1_TX/USART1_RX
(PA9/PA10) of AT32F425R8T7-7.
Please refer to AT-Link User Manual for complete details on AT-Link-EZ.
The AT-Link-EZ on board can be disassembled or separated from the AT-START-F425. In this
case, the AT-START-F425 can still be connected to the CN7 interface (not mounted before leaving
factory) of AT-Link-EZ through CN2 interface (not mounted before leaving factory), or to AT-Link, in
order to continue to program and debug the AT32F425R8T7-7.

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3.4 Boot mode selection
At startup, three different boot modes are available for selection through pin configuration.
Table 1. Boot mode selection jumper settings
Jumper
BOOT0 pin
configuration
Boot mode
JP1 to GND or be OFF
0
Boot from internal Flash memory (factory default setting)
JP1 to GND
1
Boot from boot loader code area or internal SRAM (1)
(1) Depending on the Nboot1 bit of the user system area.
3.5 External clock source
3.5.1 HEXT clock source
There are three methods to configure the external high-speed clock sources by hardware:
On-board crystal (Factory default setting)
On-board 8 MHz crystal is used as HSE clock source. The hardware must be configured: R26
and R27 ON, R28 and R29 OFF.
External oscillator from PH0
External oscillator is injected from the pin_75 of J2. The hardware must be configured: R28
ON, R26 and R27 OFF. To use PH1 as GPIO, R29 ON can be connected to the pin_6 of J2.
HSE unused
PH0 and PH1 are used as GPIOs. The hardware must be configured: R28 and R29 ON, R26
and R27 OFF.
3.5.2 LEXT clock source
There are three methods to configure the external low-speed clock sources by hardware:
On-board crystal (Factory default setting)
On-board 32.768 kHz crystal is used as LEXT clock source. The hardware must be configured:
R22 and R23 ON, R24 and R25 OFF
External oscillator from PC14
External oscillator is injected from the pin_3 of J2. The hardware must be configured: R24 and
R25 ON, R22 and R23 OFF.
LEXT unused
PC14 and PC15 are used as GPIOs. The hardware must be configured: R24 and R25 ON,
R22 and R23 OFF.

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3.6 LEDs
Power LED1
Red LED indicates that the AT-START-F425 is powered by 3.3 V.
User LED2
Red LED is connected to the PC2 pin of AT32F425R8T7-7.
User LED3
Yellow LED is connected to the PC3 pin of AT32F425R8T7-7.
User LED4
Green LED is connected to the PC5 pin of AT32F425R8T7-7.
3.7 Buttons
Reset B1: Reset button
It is connected to NRST to reset AT32F425R8T7-7 microcontroller.
User B2: User button
It is connected to the PA0 of AT32F425R8T7-7to act as a wakeup button (R5 ON and R6
OFF), or to the PC13 to acts as TAMPER-RTC button (R5 OFF and R6 ON).
3.8 USB OTG
AT-START-F425 board supports USB full-speed/low-speed host or full-speed device mode via a
USB micro-B connector (CN5). In device mode, AT32F425R8T7-7 can be directly connected to the
host through USB micro-B, and VBUS can be used as 5 V input of AT- START-F425 board. In host
mode, an external USB OTG cable is needed to connect to the external device. The device is
powered via USB micro-B interface, which is done by PD2 controlling SI2301 switch.
AT-START-F425 board has a USB type-A extension interface (CN1). This is a USB host interface
for connecting to U disk and other devices, without the need of USB OTG cable. The USB type-A
interface has no power switch control.
When the PA9 or PA10 of the AT32F425R8T7-7 is used as OTGFS_VBUS or OTGFS_ID, the JP2
jumper must select OTG1. In this case, the PA9 or PA10 is connected to USB micro-B interface,
but disconnected from AT-Link interface (CN2).

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3.9 0Ω resistors
Table 2. 0Ωresistor settings
Resistors
State(1)
Description
R4
(MCU power
consumption
measurement)
ON
When JP3 OFF, 3.3V is connected to the microcontroller
power to supply AT32F425R8T7-7.
OFF
When JP3 OFF, 3.3V can be connected to an ammeter to
measure the power consumption of the AT32F425R8T7-7.
(AT32F425R8T7-7 cannot be powered without ammeter)
R26, R27, R28, R29
(HEXT)
ON, ON, OFF, OFF
HEXT clock source comes from on-board crystal Y2
OFF, OFF, ON, ON
HEXT clock source: external oscillator from PF0, or when
PF0 and PF1 are used as GPIOs.
R22, R23, R24, R25
(LEXT)
ON, ON, OFF, OFF
LEXT clock source comes from on-board crystal Y1
OFF, OFF, ON, ON
LEXT clock source: external oscillator from PC14, or when
PC14 and PC15 are used as GPIOs.
R5，R6
(User button B2)
ON, OFF
User button B2 is connected to PA0
OFF, ON
User button B2 is connected to PC13
R32, R33
(PA11, PA12)
OFF, OFF
As USB, PA11 and PA12 are disconnected from the pin_12
and pin_13 of J1.
ON, ON
When they are not used as USB, PA11 and PA12 are
connected to the pin_12 and pin_13 of J1.
R34, R35, R36, R37
(ArduinoTM A4, A5)
ON, OFF, OFF, ON
ArduinoTM A4 and A5 are connected to ADC1_IN11 and
ADC1_IN10
OFF, ON, ON, OFF
ArduinoTM A4 and A5 are connected to I2C1_SDA and
I2C1_SCL
R38, R39
(ArduinoTM D10)
OFF, ON
ArduinoTM D10 is connected to SPI1_SS
ON, OFF
ArduinoTM D10 is connected to PWM (TMR4_CH1)
(1) Rx and RPx factory default state is shown in BOLD.

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3.10 Extension interfaces
3.10.1 ArduinoTM Uno R3 interface
Female plug J3~J6 and male plug J7 support ArduinoTM Uno R3 connector. Most of the daughter
boards built on ArduinoTM Uno R3 are applicable to AT-START-F425 board.
Note: AT32F425R8T7-7 I/Os are 3.3 V-compatible with ArduinoTM Uno R3, but not 5 V.
Note: The pin_8 of J3 is VDDA, equivalent level to VDD, without ArduinoTM Uno R3-defined AREF feature.
Table 3. ArduinoTM Uno R3 extension interface pin definition
Connector
Pin
number
Arduino pin name
AT32F425 pin name
Description
J4
(Power supply)
1
NC
-
-
2
IOREF
-
3.3 V reference
3
RESET
NRST
External reset
4
3.3V
-
3.3 V input/output
5
5V
-
5 V input/output
6
GND
-
Ground
7
GND
-
Ground
8
NC
-
-
J6
(Analog input)
1
A0
PA0
ADC1_IN0
2
A1
PA1
ADC1_IN1
3
A2
PA4
ADC1_IN4
4
A3
PB0
ADC1_IN8
5
A4
PC1 or PB9(1)
ADC1_IN11 or I2C1_SDA
6
A5
PC0 or PB8(1)
ADC1_IN10 or I2C1_SCL
J5
(Logic input/output
low byte)
1
D0
PA3
USART2_RX
2
D1
PA2
USART2_TX
3
D2
PA10
-
4
D3
PB3
TMR2_CH2
5
D4
PB5
-
6
D5
PB4
TMR3_CH1
7
D6
PB10
TMR2_CH3
8
D7
PA8
-
J3
(Logic input/output
high byte)
1
D8
PA9
-
2
D9
PC7
TMR1_CH2
3
D10
PA15 or PB6(1)
SPI1_NSS or TMR4_CH1
4
D11
PA7
TMR3_CH2 or SPI1_MOSI
5
D12
PA6
SPI1_MISO
6
D13
PA5
SPI1_SCK
7
GND
-
Ground
8
VDDA
-
VDDA output
9
SDA
PB9
I2C1_SDA
10
SCL
PB8
I2C1_SCL
J7
(Others)
1
MISO
PB14
SPI2_MISO
2
5V
-
5 V input/output

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Connector
Pin
number
Arduino pin name
AT32F425 pin name
Description
3
SCK
PB13
SPI2_SCK
4
MOSI
PB15
SPI2_MOSI
5
RESET
NRST
External reset
6
GND
-
Ground
7
NSS
PB12
SPI2_NSS
8
PB11
PB11
-
(1) Refer to Table 2 for details on 0Ω resistors.
3.10.2 LQFP64 I/O extension interface
The I/Os of AT32F425R8T7-7 microcontroller can be connected to external devices through
extension interfaces J1 and J2. All I/Os on the AT32F425R8T7-7 are available on these extension
interfaces. J1 and J2 can also be measured with oscilloscope, logic analyzer or voltmeter probe.

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4 Schematic
Figure 4. Schematic (AT-Link-EZ)

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Figure 5. Schematic (microcontroller)

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Figure 6. Schematic (power supply and peripherals)

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Figure 7. Schematic (extension interfaces)

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5 Revision history
Table 4. Document revision history
Date
Revision
Changes
2021.10.20
1.00
Initial release

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