In the previous chapter, the ISP (In System Programing) programming software and Nu-Link2-Pro program debugger were introduced; product systems can be upgraded using these two tools. Furthermore, if users choose to connect products using the UART interface, the Nu-Link2-Me included with the NuMaker evaluation board can also be used directly for connection. Nuvoton provided very flexible ISP programming methods; in terms of tool usage, in addition to Nu-Link2-Pro or Nu-Link2-Me, clients can also use tools they developed themselves or by third-parties as to the host terminal. In terms of software usage, Nuvoton also provided the source code and executable file of the ISP programming software directly, allowing users to perform customized settings. Next, the use of general methods with Nu-Link2-Pro will be used to explain the ISP process.

ISP is divided into four steps. First, the ISP Bootloader must be prepared. Next, the Bootloader must be programmed onto the chip; next, set the connection interface, and finally, use the ISP programming software to program the product to complete the system upgrade. The following will use the SPI interface to explain how to connect products to Nu-Link2-Pro using the SPI interface to perform an ISP system upgrade.

1. Prepare the ISP Bootloader

• ISP Bootloader code

The ISP Bootloader codes for the various interfaces are stored in BSP; users can choose according to the connection interface set. Take the SPI interface, for example. The path of its code is SampleCode/ISP/ISP_SPI.

• Generate the Bin file

Open the Bootloader project that corresponds to IDE (such as arm KEIL/ IAR/ NuEclipse), and compile it to generate the Bin file. Take the SPI interface, for example. ISP_SPI.bin will be generated after the compilation.

2. Bootloader programming

• Connect the product

Use SWD to connect Nu-Link2-Pro with the garget chip on the product (Figure One); connect the other end of Nu-Link2-Pro to the PC through the USB connection.

Figure 1. Connecting the target chip to Nu-Link2-Pro through SWD

• Program setting

Use ICP to connect to Nu-Link2-Pro and perform program settings (Figure 2).

1) Load the Bootloader to LDROM

2) Select LDROM activation for the configuration bit

3) Select LDROM and the configured area for the programming section

Figure 2. Bootloader program setting

• Start programming

Press the Start button to program the Bootloader to LDROM.

3. Set the connection interface

If the SPI interface is used to connect Nu-Link2-Pro and the target chip on the product, six cables must be set: SS/ CLK/ MOSI/ MISO/ VDD33/ VSS (GND); connect the other end of Nu-Link2-Pro to the PC (Figure 3). For the configuration of different interfaces, refer to 3.3 Bridge Interface Pin Definition and Function Connection in the Nu-Link2-Pro user manual.

Figure 3. ISP_SPI interface connection diagram

For the default pin configuration of the various interfaces, check the main program code of the ISP Bootloader. Take M487 in Figure 3, for example. In the main program code of its ISP_SPI (Figure 4), the pin configuration is SS – PH9/ CLK – PH8/ MOSI – PE0/ MISO – PE1.

Figure 4 ISP_SPI main program code

4. ISP setting (Figure 5)

• Select the connection interface

Select according to the interface setting in Step 3; for example I²C/ SPI/ CAN/ RS485/ UART.

• Connect the product

Click the Connect button and reset the target chip on the product; this will connect to the target chip through the selected interface.

• Load the upgrade Bin file

Place the upgrade Bin file to program in APROM.

• Config Bits setting

Confirm whether the Config Bits settings are correct.

• Program setting

Select the program location as APROM, and select the Reset and Run option.

• Start programming

Press the Start button, and the ISP programming software will start programming the upgrade file to the target chip through the selected connection interface.

Figure 5. ISP setting steps

Nuvoton provided integrated development environment IDE, the NuMaker evaluation board, supported packaged software BSP for the evaluation board, and PinConfigure/ PinView for the development stage; as for the mass production stage, there is the ICP programming software that can perform online programming, offline programming, and one-to-many programming. Use the ISP programming software and Nu-Link2-Pro to complete product upgrades for the upgrade stage without removing the chip. There are sufficient tools for clients to use at the various stages to reduce client burden and improve work efficiency. The complete ecosystem represents Nuvoton’s customer-oriented core value; in the future, Nuvoton will continue to enhance and enrich the ecosystem, hoping to bring clients and the entire industry better user experiences.