Cannot flash LPC55S69J MCU
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We are having issues flashing the LPC55S69J MCU. Flashing is performed via SWD.
This is the error message the IDE shows: Wire ACK Fault in DAP access
We've confirmed we have the right MCU orientation, correct voltages, etc. We are using the same setup that successfully flashes the LPC55S69-EVK.
Is there a particular pin configuration needed for the LPC55S69 MCU to flash? Anything missing from the setup detailed?
** Setup **
Hardware platforms used:
- Custom designed board
- Breakout board with LPC55S69J MCU soldered on (Digikey PN: PA0096-ND)
- MCU-LINK board
Hardware notes:
MCU: LPC55S69JBD64K
SWDIO: pulled up via 100k; connected to pin 5 of MCU
SWCLK: pulled down via 100k; connected to pin 6 of MCU
VBAT_PMU pulled high 3V3
Reset line observed high; pulls low from programmer
All VDD pins externally connected to 3V3
All VSS pins externally connected to ground
USB1 (high speed) used
Setup information:
NXP Eval kit used: LPC55S69-EVK
NXP Programmer: MCU-LINK
PC/IDE info:
Product: MCUXpresso IDE
Version: MCUXpresso IDE v11.6.0 [Build 8187] [2022-07-13]
Operating system: Windows 10
VM: OpenJDK 64-Bit Server VM (64 bit)
NXP LPCXpresso55S69 Development Board: https://www.nxp.com/design/development-boards/lpcxpresso-boards/lpcxpresso55s69-development-board:LP...
NXP MCU-Link Debug Probe: https://www.nxp.com/design/microcontrollers-developer-resources/mcu-link-debug-probe:MCU-LINK
Log information generated the IDE:
MCUXpresso IDE RedlinkMulti Driver v11.6 (Jul 12 2022 16:58:24 - crt_emu_cm_redlink build 4)
Found chip XML file in C:/ (removed)
( 5) Remote configuration complete
Reconnected to existing LinkServer process.
Connecting to probe 1 core 0 (using server started externally) reports:
'Ee(42). Could not connect to core.'
Retrying...
Reconnected to existing LinkServer process.
Server OK but no connection to probe 1 core 0 (after 3 attempts) - Ee(42). Could not connect to core.
Failed on connect: Ee(42). Could not connect to core.
No connection to chip's debug port
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Hi Jun Zhang,
Thank you for the reply. I was able to get the MCU to flash. We provided VDD_PMU with 1.1V and flashing worked after this.
Our application does not use the internal DCDC converter. Could you confirm if the LCP55S69 MCU will function correctly if we do not use the built in DCDC converter and just supply VDD_PMU pin with 1.1V?


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Hi ay44
Please refer
https://www.nxp.com.cn/docs/en/application-note/AN12325.pdf
to design LPC55S69 DCDC
This post includes DCDC circuit detection.
For SWD interface design, please refer
https://community.nxp.com/t5/LPCXpresso-IDE-FAQs/Design-Considerations-for-Debug/m-p/469565#M44
Hope this helps,
Jun Zhang
