In December of last year, I learned that STMicroelectronics (ST) expanded its low-cost evaluation board Nucleo series, launching the Nucleo 144 series evaluation board based on Nucleo 64 and Nucleo 32. After a few months of waiting, I finally got to see it!

Thanks to the EEWORLD community and the administrators for giving me the opportunity to evaluate a NUCLEO-F446ZE evaluation board. Today, let’s experience the new favorite of Nucleo together.

My review will include:

1. Unboxing

2. Powering on

3. Overview

4. Development

5. Summary

1. Unboxing

Upon receiving the NUCLEO-F446ZE development board, the packaging is still in the familiar style—blister packaging, but this time it is much larger, even bigger than the previous STM32F469-Discovery. In hand, it is about the size of a palm, doesn’t it feel grand? Surprising?

Figure 1-1 NUCLEO-F446ZE Development Board Packaging

Figure 1-2 NUCLEO-F446ZE Development Board

The Nucleo 144 development board is a low-cost Nucleo series launched by STMicroelectronics for users. So far, three series have been launched: Nucleo32, Nucleo64, and Nucleo144, covering low, medium, and high MCU products in the STM32 series. The pin packaging also includes major mainstream MCUs in large, medium, and small sizes, forming a relatively complete ecosystem. The following picture shows the currently launched Nucleo evaluation boards by ST. We can see that Nucle-F446ZE belongs to the high-performance multi-pin range.

Figure 1-3 Nucleo Development Board Series

Just right, I have all three series development boards on hand, let’s compare them together. The smallest on the left is the Nucle-F031K6 development board, which has an onboard 32-pin STM32F031K6 microcontroller. In the middle is the earliest launched Nucleo 64 series development board Nucleo-F446RE, which has an onboard 64-pin STM32F446RE microcontroller, and on the right is this Nucle-F446ZE, which has an onboard 144-pin STM32F446ZE microcontroller. You can see that the Nucle-F446ZE evaluation board has more interfaces and richer resources.

Figure 1-4 Nucleo Development Board Comparison

Let’s take a closer look at this Nucleo-F446ZE development board. Although the size of the development board has increased significantly, we can still see the familiar features of the previous Nucleo series evaluation boards:

(1) The upper part of the development board has an onboard ST-LINK V2.1 emulator debugger, allowing users to program and debug the onboard MCU without incurring additional costs, and it is designed in a card slot form that can be opened for separate use;

(2) The central high-performance main control chip STM32F446ZE microcontroller forms the minimum system, with an ARM Cortex-M4 core with DSP and FPU capabilities, a main frequency of up to 180 MHz, 512kB flash memory, and LQFP144 packaging.

(3) It provides two types of interfaces: ST Zio interface, which includes Arduino™ Uno Revision 3 interface, while still providing ST morpho interface, bringing out all pins for user use, but this part of the interface is not soldered with pin headers, which is a small regret;

(4) Besides the STM32F446ZE minimum system, the development board provides very few onboard peripheral resources, user button, reset button, and user LED. However, the positions of the user button and reset button have changed significantly, no longer in the middle of the development board, but at the very bottom, which is more user-friendly. When designing expansion boards, users basically do not need to worry about them being covered. Additionally, the number of user LEDs has increased from 1 to 3. Moreover, the Nucleo-144 series development board adds USB-OTG and Ethernet interfaces, which is a major feature of this board. However, the Nucleo-F446ZE development board I received only has a USB-OTG interface, and the original Ethernet interface circuit exists, but the components are all soldered. This is also a significant regret of this development board because the onboard STM32F446ZE microcontroller does not have Ethernet functionality in its internal peripherals!

Figure 1-5 NUCLEO-F446ZE Development Board Front

After looking at the front of the development board, let’s flip it over to see the back. Consistent with previous styles, the back is basically configured with solder bridges. On the previous Nucleo-64 development board, solder bridges were only on the bottom layer of the circuit board, while on the Nucleo-144 development board, solder bridges are set on both the top and bottom circuit boards, but the top layer solder bridges are all named in SBXX format, while the bottom layer solder bridges are all named in SB1XX format.

Figure 1-6 NUCLEO-F446ZE Development Board Back

On the four corners of the back of the development board, you can see that the pin headers have been soldered, and four jumper caps have been added. These four positions are exactly the grounding (GND), slightly higher than the already soldered ST Zio interface pin headers, forming four small support bases for the development board. This design is quite clever and user-friendly.

Figure 1-7 NUCLEO-F446ZE Development Board Base

Another point to praise is that on the new Nucleo-F446ZE development board, all pin descriptions are warmly marked on the silk screen of the circuit board, making it very convenient to find pins without having to peel off the circuit schematic and count each pin one by one, often leading to mistakes!

Figure 1-8 NUCLEO-F446ZE Development Board Interface 1

Figure 1-9 NUCLEO-F446ZE Development Board Interface 2

Figure 1-10 NUCLEO-F446ZE Development Board Interface 3

Let’s take a look at the instruction page in the packaging box; the style is similar to before. It shows the model of the development board at the top, a basic feature description of the development board at the bottom left, and the interface description of the development board on the right.

Figure 1-11 NUCLEO-F446ZE Development Board Instruction Page Front

Is it the same as before? Actually, there are still slight differences. The model of the development board in the upper left corner now officially uses names like Nucleo-144 and Nucleo-64, which were not explicitly referred to by the official before.

Figure 1-12 NUCLEO-F446ZE Development Board Instruction Page Comparison

The back of the instruction page contains a guide on how to use the development board. If it is your first time using the Nucleo series development board, it is recommended to read this carefully, as it describes how to run the onboard demo program. Additionally, it includes system configuration requirements for using the development board and recommended IDEs.

Figure 1-13 NUCLEO-F446ZE Development Board Instruction Page Back

2. Powering On

Upon receiving the development board, I wanted to get it up and running as soon as possible. Of course, the onboard demo program provided by the official is a good choice.

1. To run the onboard demo program, you need to confirm the jumper positions on the Nucleo-F446ZE development board:

(1) Jumper PWR-EXT (JP1) should be confirmed to be disconnected

(2) Power selection jumper JP3 should confirm that U5V is selected and shorted

(3) Jumper IDD (JP5) should be confirmed to be shorted

(4) CN4 interface should be shorted

2. Use a USB A to micro-B USB cable to connect the CN1 interface of the development board to the computer, which can power the development board. You can see the power indicator light LED (LD6) on the development board is lit, and the ST-LINK indicator light LD4 is also on.

3. At the same time, the system starts running the program:

(1) The green user LED1 starts flashing at a frequency of 2Hz, with a 0.5-second cycle.

(2) Press the blue user button once, the green user LD1 stays lit, and LD2 (blue LED) flashes at a frequency of 1Hz.

(3) Press the blue user button twice, the green user LD1 and LD2 stay lit, and LD3 (red LED) flashes at a frequency of 0.5Hz.

(4) Press the blue user button three times, the green user LD1 flashes at a frequency of 2Hz, and LD2 and LD3 are lit.

Then repeat pressing the blue user button, following the order of LD1, LD2, LD3, where each time one LED flashes while the other two remain lit.

Figure 2-1 Official DEMO Demonstration

3. Overview

Having just received the NUCLEO-F446ZE development board, I need to get to know the resources of the development board well for further use.

1. Structure

The Nucleo-144 development board is a low-cost evaluation board based on the STM32 microcontroller with LQFP-144 packaging provided by STMicroelectronics. The structural design of the development board still follows the style of the previous Nucleo-64 series, with the development board divided into two areas: the upper part is the ST-LINKV2 area, and the lower part is the microcontroller’s minimum system, onboard peripherals, and interface circuit. The ST-LINK part can be easily cut in the middle for separate use. At this point, the Nucleo-F446ZE development board is divided into two independent small boards.

The minimum system board of the STM32F446ZE can also be used separately, but it should be noted that the minimum system board can only be powered using the VIN, E5V, and 3.3V pins of the ST Morpho full expansion interface or the VIN and 3.3V pins of the ST Zio interface.

Figure 3-1 NUCLEO-144 Development Board Structure

The overall layout introduction of the development board can be seen in the figure below. The part of the chip description document provided by STMicroelectronics has improved compared to before, using 3D simulation diagrams for display, making it more convenient.

Figure 3-2 NUCLEO-F446ZE Development Board Front Layout

Figure 3-3 NUCLEO-F446ZE Development Board Back Layout

2. STM32F446ZET6 Microcontroller

The Nucleo-F446ZE development board has an onboard high-performance LQFP-144 packaged microcontroller STM32F446ZE.

Figure 3-4 NUCLEO-F446ZE Development Board Main Controller

The STM32F446ZE belongs to the high-performance STM32F4 microprocessor of STMicroelectronics. In the STM32F446xx series, there are eight models, as shown in the figure below. The main differences are in packaging forms, pin counts, and internal peripherals. The MCU onboard the Nucleo-F446ZE development board is the highest in performance and configuration among the STM32F446xx series, with 512KB of flash memory, 144-pin LQFP packaging, and a main frequency of up to 180 MHz.

Figure 3-5 STM32F446 Microcontroller Series

The following figure shows the internal structure diagram of the STM32F446ZE chip.

Figure 3-6 STM32F446ZET6 Internal Structure Block Diagram

The main features of STM32F446ZET6 are:

Based on ARM Cortex-M4 core processor, supports a maximum main frequency of 180 MHz, 512 KB flash, and 128 KB SRAM.

Supply voltage ranges from 1.7 V to 3.6 V.

Adaptive Real-Time Accelerator (ART Accelerator™), supports executing code from Flash with zero wait states.

Features low-power modes such as Sleep, Stop, and Standby, effectively reducing system power consumption.

Includes three 12-bit 2.4MSPS ADCs, up to 24 channels, and two 12-bit DACs.

Includes up to 17 timers: 2 watchdogs, 1 SysTick, 12 16-bit general-purpose timers, and 2 32-bit high-speed timers, with input capture, output compare, and PWM functions.

On the external pins, 114 out of 144 pins have interrupt functions, 111 have 90MHz high-speed I/O, and 112 have 5V tolerance.

Interface features include one SPDIF receiver, up to 4 I2C interfaces, up to 4 USART and 2 UART interfaces (supporting LIN, IrDA), 2 SAI interfaces, 2 CAN interfaces, and 1 SDIO interface.

Includes an external memory controller for SRAM, PSRAM, SDRAM/LPSDR DRAM, Flash NOR/NAND, etc., with a 16-bit data bus. Supports parallel LCD interface in 8080/6800 mode. These features provide better support for more complex LCD control schemes for STM32F446ZET6.

Includes USB-OTG functionality for connecting different devices or mobile devices for data exchange.

Supports 8-bit or 14-bit parallel camera interfaces.

3. ST-LINK/V2-1

The Nucleo-F446ZE development board has an embedded ST-LINK/V2-1 programming debugger, which connects directly to the target MCU via the SWD interface, allowing for programming and debugging of the target MCU while also providing USB interface virtual serial port, USB interface storage, and USB power management functions. It should be noted that the ST-LINK/V2-1 programming debugger does not support SWIM interface and operates at voltages below 3V.

The ST-LINK/V2-1 programming debugger can program and debug not only the onboard STM32F446ZE but also has a reserved external SWD interface for programming and debugging other STM32 series microcontrollers.

The following figure shows the use of ST-LINK/V2-1 programming debugger to program and debug the onboard MCU. It is important to note that the CN4 jumper must be shorted.

Figure 3-7 ST-LINK/V2-1 Programming Debugging Onboard MCU

The following diagram shows using ST-LINK/V2-1 to program and debug external MCUs, where it is important to note that the CN4 jumper must be disconnected, using CN6 for external MCU.

Figure 3-8 ST-LINK/V2-1 Programming Debugging External MCU

The definitions of CN6 from top to bottom are shown in the table below.

Table 3-1 ST-LINK/V2-1 Interface

Comparing the Nucleo-F446ZE development board with the Nucleo-F446RE development board’s ST-LINK/V2-1, at first glance, they look similar, but upon closer inspection, there are still differences:

The Nucleo-F446RE development board uses a USB-B type interface, while the Nucleo-F446ZE development board uses a smaller micro-B interface.

The packaging of the crystal oscillator in the ST-LINK part is different.

Figure 3-9 Comparison of Nucleo-F446RE and Nucleo-F446ZE ST-LINK

In fact, the biggest difference is that the Nucleo-F446ZE’s micro-B interface has an additional USBLC6-2SC6 chip below it. The circuit diagram is shown below. This chip is a low-capacitance ESD protector designed to protect single-chip devices from ESD at high-speed interfaces (such as USB 2.0, Ethernet links, and video lines). The extremely low line capacitance ensures signal integrity and eliminates the impact of ESD shocks.

Figure 3-10 ST-LINK USB Circuit of Nucleo-F446RE

Figure 3-11 ST-LINK USB Circuit of Nucleo-F446ZE

4. Perfectly Compatible Expansion Interfaces

The Nucleo-F446ZE development board is designed to be fully compatible with the existing STM32 development ecosystem, including dedicated application expansion plug-in boards. This means that developers can directly apply the expansion boards designed for the NUCLEO-64 development board to the Nucleo-F446ZE development board. This feature is highly commendable, achieving compatibility between different development boards.

Figure 3-12 Nucleo-F446RE Interface Description

Figure 3-13 Nucleo-F446ZE Interface Description

The new Nucleo-F446ZE development board achieves unlimited application expansion functions through three interfaces. In addition to the Arduino™ Uno and ST morpho connectors on the existing Nucleo-64 board, it also includes an ST zio connector. These three types of connectors allow developers to use all general-purpose I/O pins of the STM32 microcontroller, easily realizing various functional evaluations.

5. USB FS OTG or Device

One of the major features of the Nucleo-F446ZE development board is that it has a user USB interface CN13, which can achieve full-speed communication between the computer and the onboard STM32F446RE microcontroller via a Micro USB-AB connector.

It should be noted that while the Nucleo-F446ZE development board has two USB interfaces, one for ST-LINK and one for this USB-OTG interface, only the ST-LINK USB interface provides power to the development board. The user’s Micro–AB USB does not provide power to the development board to prevent damage to the I/O ports of the main controller.

There are two LED indicators on the USB interface circuit: one is a green LED (LD8), which lights up when the Nucleo-F446ZE development board is used as a USB host when the power switch U12 is turned on or when it is used as a USB device when the VUSB line is powered by the host; the other is a red LED (LD7), which lights up when there is an overcurrent on VUSB when used as a USB host.

This part of the circuit is as follows:

Figure 3-14 User USB Circuit

Using MCU pins and functions:

Table 3-2 USB Interface Pins

5. Ethernet Interface

Upon receiving the Nucleo-F446ZE development board, I found that the Ethernet interface on the board was empty, with no components. After checking the information, I found that the STM32F446ZE microcontroller does not have Ethernet functionality, which is quite regrettable as I cannot evaluate this part of the functionality!

The other functions of the Nucleo-F446ZE development board are basically similar to the previous Nucleo-64 series development boards, so I won’t repeat them here.

4. Development

Having a clearer understanding of the development board, I can proceed to the next step of development.

1. Environment

Before development, of course, I need to prepare development tools and set up the development environment. STMicroelectronics provides a wealth of development tools for NUCLEO development boards. In terms of IDE, it supports mainstream IDEs, including MDK, IAR, GCC-based IDEs, etc. Additionally, it supports ARM’s latest cloud development Mbed. In terms of software, ST provides standard libraries and HAL libraries for STM32, along with a large number of project examples and development templates to help engineers quickly develop STM32 projects. Furthermore, ST has released the STM32 CUBEMX configuration tool, which can complete STM32 microcontroller initialization configuration work using a graphical interface. All these components form a simple and easy-to-use ecosystem.

I wanted to experience the Mbed development of the new Nucleo-F446ZE, but when I connected to the Mbed website, it showed that Nucleo-F446ZE development is not supported yet. It seems that the Nucleo-F446ZE is too new, and it is expected to be officially supported for Mbed development in the second quarter of 2016.

Figure 4-1 Mbed Not Yet Supported for Nucleo-F446ZE

Since that’s the case, I can only use the traditional development method. I chose the familiar MDK+CUBEMX+HAL library method.

(1) First, download the latest MDK5.18 from the MDK official website: http://www.keil.com/arm/mdk.asp.

Figure 4-2 MDK Download Page

(2) Next, download the latest software support package MDK5 Software Packs from the MDK official website, version Keil.STM32F4xx_DFP.2.7.0.pack, at: http://www.keil.com/dd2/Pack/.

Figure 4-3 MDK5 Software Packs Download Page

(3) Download CUBEMX from the ST official website, version 4.13, at: http://www.st.com/web/catalog/to … 961/SS1533/PF259242.

Figure 4-4 STM32 CUBEMX Download Page

(4) Download the HAL library for STM32F4, version: 1.11.0, at: http://www.st.com/web/en/catalog/tools/PF259243.

Figure 4-5 STM32F4 Series MCU Library Download Page

The software installation is relatively simple, so I won’t repeat it here.

Before development, ensure that the ST-LINK emulator debugger of the Nucleo-F446ZE development board is properly installed and the firmware is updated. When the development board is connected to the computer, the corresponding device should appear in the device manager.

Figure 4-6 Nucleo-F446ZE Development Board Recognized Device

2. Development

After setting up the development environment, the next step is to develop my project and experience the convenience of the STM32 ecosystem provided by STMicroelectronics.

I won’t share the basic software usage here, as I believe there are many methods in the community.

The Nucleo-F446ZE development board does not have an Ethernet interface, so the USB interface is one of the biggest highlights of this board. Let’s experience it.

Starting from the existing project examples provided by ST, it’s a good choice to quickly experience the USB functionality of the Nucleo-F446ZE development board, especially if you are not very familiar with its USB functionality.

ST has provided a wealth of examples for the Nucleo-F446ZE development board, located at: \STM32Cube\Repository\STM32Cube_FW_F4_V1.11.0\Projects\STM32F446ZE-Nucleo.

Figure 4-7 Nucleo-F446ZE Development Board Example

In the Applications folder of the above path, there are comprehensive examples regarding USB, divided into host and device types.

Figure 4-8 Nucleo-F446ZE Development Board USB Example

After reviewing, I found that many examples are comprehensive and therefore require not only the Nucleo-F446ZE development board itself but also some expansion boards, such as LCD screens, etc.

After some selection, I finally found a standard HID example in USB device mode that implements mouse functionality, which only requires the development board itself. The path is: STM32Cube\Repository\STM32Cube_FW_F4_V1.11.0\Projects\STM32F446ZE-Nucleo\Applications\USB_Device\HID_Standalone.

Opening it in MDK, you can see that the project directory structure is very clear.

Figure 4-9 HID_Standalone Example

The entire project example is very concise and includes relevant comments. I won’t analyze it further; I’ll simply compile the program and find no errors. Then I’ll download and run the program, and the three LEDs on the development board start flashing.

Connecting the USB cable to the Micro–AB USB interface of the development board and to the computer, you will see the green LED next to the user USB interface lit up, and the mouse on the computer will move back and forth horizontally. At the same time, a new USB mouse device will appear in the device manager.

Figure 4-10 HID_Standalone Example Demonstration

Figure 4-11 HID_Standalone Example Recognized Mouse Device

The entire process went very smoothly. Of course, you can spend some time studying the program thoroughly, and I believe you will gain a lot. Additionally, you can add some features based on the example, such as making the mouse perform complex movements on the screen or adding mouse click and double-click actions, etc.

Finally, while reviewing the official examples provided by ST and combining personal experience, I would like to make a few small suggestions:

(1) The comprehensive examples provided in the official library should ideally be based on the resources of the development board itself, minimizing the use of expansion resources, as not everyone has expansion boards. For example, many examples use a 1.8-inch TFT screen, which is likely not available to everyone. Even if one has it, the control chips for the TFT screens may not match. For instance, the example uses an ST7735S driver IC, while I have several that are not this one. To use the examples, one would either need to purchase this expansion board, which I found to be quite expensive.

(2) The library examples provided by the official are all based on the HAL library, but they do not fully utilize the STM32 CUBEMX graphical development tool. In other words, I did not see any examples that were developed based on the code generated by the STM32 CUBEMX software, nor were there CUBEMX examples provided. The purpose of releasing the STM32 CUBEMX software is to simplify the development process, but even ST does not provide many reference examples, increasing the learning difficulty and causing some inconvenience. Therefore, I hope that STMicroelectronics can provide more examples based on CUBEMX software in future updates of the HAL library, including CUBEMX project files.

5. Summary

In conclusion, the Nucleo-F446ZE development board launched by STMicroelectronics belongs to the STM32 Nucleo-144 series, further expanding the original STM32 development ecosystem. The new Nucleo-144 development board is affordable and compact, featuring an onboard STM32F446ZET6 processor based on the ARM Cortex-M4 core, supporting a maximum main frequency of 180 MHz, 512 KB flash memory, and 128 KB SRAM. The development board comes with an ST-LINK programming debugger, facilitating system debugging and development. The Nucleo-F446ZE development board achieves unlimited application expansion functions through three interfaces, in addition to the Arduino™ Uno and ST morpho connectors on the existing Nucleo-64 board, it also includes an ST zio connector, fully compatible with the existing STM32 development ecosystem, including dedicated application expansion plug-in boards. These three types of connectors allow developers to utilize all general-purpose I/O pins of the STM32 microcontroller. The Nucleo-F446ZE development board supports multiple popular IDEs and provides users with complete software libraries and graphical development tools. Whether for electronic enthusiasts and students or the most experienced professional system developers, the Nucleo-F446ZE development board can easily achieve various functional evaluations.