When using the SW connection, the RST pin of the FS32K144UAT0VLLT still shows a triangular wave after unlocking. Without connecting the RST pin, the host computer cannot connect to the microcontroller. A J-LINK uses SWDIO and SWCLK, with GND connected to the microcontroller FS32K144UAT0VLLT. The program download circuit uses 5V for both VCC and the microcontroller. The RST pin has a triangular wave: f=1.8KHZ, 2.6Vp-p triangular wave: 3. When entering "unlock" in J-Link, Kinetis displays an error and cannot connect: IV. The J-Link connection to the microcontroller's 97 pin PTA5 (*JTAG_TRST/*RESET) via the RST reset pin is successful, and decryption is successful. Does this mean decryption was successful? 5. When connecting the circuit board using Keil uVision5, the microcontroller cannot be connected without using RST; RST is required for connection. 9.png9.png9.png9.png9.png9.png And the triangular wave on the reset pin is still present, as shown in the following figure: Question for NXP instructors: This circuit board (using the FS32K144UAT0VLLT microcontroller) previously worked fine when only SWDIO, SWCLK, and GND were connected, allowing for normal program downloads. Why is it that this time, program downloads only occur after connecting RST? What could be the reason? Thank you! 回复: FS32K144UAT0VLLT使用SW连接,解锁后RST管脚仍然有三角波,不连接RST管脚上位机不能和单片机连接。 Hi
Without RESET_b connected, J-Link cannot control the reset timing of the S32K1; intermittent connection failures may occur if the user program, watchdog timer, low-power mode, or pin multiplexing affects the debug port.
Because there is no code in the Flash (e.g., in a new chip, the Flash is empty), the MCU will continuously and periodically reset due to a core lockup. Furthermore, due to the external RC circuit, the square wave becomes a triangular wave.
Once you download a new, working program, the RESET_b pin will return to a high level.
Best Regards, Robin 回复: FS32K144UAT0VLLT使用SW连接,解锁后RST管脚仍然有三角波,不连接RST管脚上位机不能和单片机连接。 Dear teachers: Sorry, the illustrations for the question I posted yesterday were not properly matched, making it very messy and unclear. I'm reposting it today, and I hope all the teachers can provide explanations as soon as possible! When using the SW connection, the RST pin of the FS32K144UAT0VLLT still shows a triangular wave after unlocking. Without connecting the RST pin, the host computer cannot connect to the microcontroller. A JLINK uses SWDIO and SWCLK, with GND connected to the microcontroller FS32K144UAT0VLLT. The program download circuit uses 5V for both VCC and the microcontroller. 11.png11.png11.png11.png11.png11.png 2. The RST pin shows a triangular wave: f=1.8KHZ, 2.6Vp-p triangular wave: 22.png22.png22.png22.png22.png22.png 3. When entering "unlock" in J-Link, Kinetis displays an error and cannot connect: 33.png33.png33.png33.png33.png33.png 4. Add the RST reset pin to the J-Link and connect it to the microcontroller's 97 pin PTA5 (*JTAG_TRST/*RESET). Connection successful, decryption successful. 44.png44.png44.png44.png44.png44.png 5. When using Keil uVision5 to connect the circuit board, you cannot connect the microcontroller without using RST; you can only connect the microcontroller by using RST. And the triangular wave on the reset pin is still present, as shown in the following figure: 22.png22.png22.png22.png22.png22.png 回复: FS32K144UAT0VLLT使用SW连接,解锁后RST管脚仍然有三角波,不连接RST管脚上位机不能和单片机连接。 Teacher: The above text is miswritten. Please see the Word document below; it's the same issue. Thank you! 回复: FS32K144UAT0VLLT使用SW连接,解锁后RST管脚仍然有三角波,不连接RST管脚上位机不能和单片机连接。 Robin_Shen: How are you! Hello Manager, I'm very happy to see your reply. I've learned a lot, thank you! We have a total of 4 experimental boards. One of them connected normally after the program was downloaded. It can be connected using only SWDIO, SWCLK, and GND. The RST pin has returned to a high level. However, after downloading the program to the other three chips, the RST pin still shows a triangular wave. The J-link cannot connect to the FS32K144UAT0VLLT microcontroller using only the SWDIO, SWCLK, and GND pins; it only connects to the RST pin for a proper connection. How should this be handled? Thank you! 回复: FS32K144UAT0VLLT使用SW连接,解锁后RST管脚仍然有三角波,不连接RST管脚上位机不能和单片机连接。 Robin_Shen: Manager: Hello, I have some questions and would like to ask you further: 1. When using SWDIO, SWCLK, and GND to download programs on the FS32K144UAT0VLLT, does the RST pin also exist in normal operation? Does the RST connection also fall under SWD mode downloading? 2. Some circuit boards only use three wires (SWDIO, SWCLK, GND) to download programs, while others require four wires (SWDIO, SWCLK, GND, RST). Are both considered normal downloads? Are they both considered normal downloads in SWD mode? Thanks! 回复: FS32K144UAT0VLLT使用SW连接,解锁后RST管脚仍然有三角波,不连接RST管脚上位机不能和单片机连接。 After successfully downloading the correct program, RESET_b should remain high. (AN5426 Hardware Design Guidelines for S32K1xx Microcontrollers (Rev.))December 6, 2021).pdfThe recommended debugging port includes RESET_b, and it is recommended to modify the hardware. 回复: FS32K144UAT0VLLT使用SW连接,解锁后RST管脚仍然有三角波,不连接RST管脚上位机不能和单片机连接。 SWD standard communication does not mandate a connection to RESET_b, but reliable programming, Connect Under Reset, and recovery scenarios for the S32K1 heavily rely on it, so it is recommended to use it as a mandatory signal handler for debugging.
However, the current S32K1 is brand new and has no program installed, so the chip is repeatedly resetting. If RESET_b is not connected to J-Link, J-Link cannot reliably execute true Connect Under Reset, so some chips can "happen" to catch the window, while others cannot.
If you have a PEMicro debugger, you can use https://community.nxp.com/t5/S32K/S32K144-D2-RED-LED-is-ON-always/mp/1567621The P&E Recovery Utility tool in the document halts the MCU during repeated power-on cycles.
Your J-Link should also be able to follow the methods described in the tools above: The J-Link initially went through a cycle of connecting/attaching/halting; Then power off and then power on the target board; Try to capture SWD after Power-on Reset and before the application or blank chip runs out of control.
You can refer to the S32K1xx_MassErase_Read_MDM-AP_Registers_Command_Script.txt command script in the "S32K1xx Series MCU Application Guide: Analysis of Chip Lockup Reset Causes and Detailed Explanation of Recovery Methods" .
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