Fixing RESET & DFU issues on old PortaPack H2+ PCB v3.6
This procedure fixes two issues found on some old PortaPack H2+ PCB v3.6 units:
- The RESET push button freezes the device instead of resetting it.
- The DFU push button does not work correctly with current Mayhem firmware.
The problem can be fixed by updating the PortaPack CPLD firmware.
IMPORTANT: This procedure has been validated only on the specific hardware configuration described below.
Do not use it on other PortaPack revisions unless they have been independently verified as compatible.
1. Firmware prerequisite
Before starting this procedure, make sure your PortaPack is running a recent Mayhem firmware version that provides the USB serial console CPLD commands used in this guide.
You can do it , connecting your device to Mayhem Hub through USB ,https://hackrf.app/ just updating your Mayhem fw with latest available nightly .
2. Check that your hardware matches
Before doing anything, visually check that your PortaPack is:
- PortaPack H2+
- PCB version 3.6
- CPLD package: QFP100
Then connect the PortaPack to Mayhem Hub and open the USB serial console.
Run:
cpld_info portapack
The affected units validated with this procedure reported:
CPLD IDCODE: 0x00025610
CPLD Model: AGM AG256SL100
CPLD firmware checksum: 0x17DDE5B1
Proceed only if ALL of the following conditions match:
PortaPack H2+ → PCB v3.6 → AGM AG256SL100 (QFP100) → original CPLD checksum 0x17DDE5B1
If any of these conditions do not match, do not use this procedure.
3. Get the CPLD programming file
Use the official Mayhem CPLD programming file (in the official remote Mayhem GitHub or in your local fork repo):
hardware/portapack_h4m/CPLD/Supra/portapack_h4m_cpld.prg
File name:
portapack_h4m_cpld.prg
Verify the file on your computer
Before uploading it to the PortaPack SD card, verify its SHA256, (using any of those below three options).
1-) Linux:
sha256sum portapack_h4m_cpld.prg
2-) Windows PowerShell:
Get-FileHash .\portapack_h4m_cpld.prg -Algorithm SHA256
3-) Windows Bash Shell:
sha256sum portapack_h4m_cpld.prg
Expected SHA256:
210c891c0207ea705fce6282c592d91f421c18e306aa91d8bd3af57d41cc0977
Do not continue if the SHA256 does not exactly match.
4. Upload the PRG file to the SD card
Using Mayhem Hub, upload (clicking second icon starting from left) :
portapack_h4m_cpld.prg
to the root directory of the PortaPack SD card.
After uploading, verify that the file is present:
ls /
You should see:
portapack_h4m_cpld.prg
Verify the SD uploaded file (that it was correctly uploaded without any corruption)
Use the Mayhem Hub serial command:
crc32 /portapack_h4m_cpld.prg
Expected CRC32:
0x050D8A24
Do not continue if this value does not exactly match.
5. Important checksum clarification
Do not confuse these three different checksum values:
| Check | Expected value |
|---|---|
| PRG file SHA256 | 210c891c0207ea705fce6282c592d91f421c18e306aa91d8bd3af57d41cc0977 |
| Uploaded PRG file CRC32 | 0x050D8A24 |
| CPLD checksum after programming | 0x20F48814 |
WARNING: The original factory CPLD firmware with checksum
0x17DDE5B1cannot currently be restored from a simple CPLD readback/dump.Do not continue unless the board revision, CPLD model/IDCODE, original CPLD checksum, PRG SHA256 and uploaded-file CRC32 all exactly match the values documented above.
6. Program the CPLD
Run:
cpld_write portapack eeprom portapack_h4m_cpld.prg
The programming process should report:
CPLD IDCODE: 0x00025610
CPLD Model: AGM AG256SL100
Reading file...
Magic found: 3397A006
Writing data to CPLD...
New CPLD firmware checksum: 0x20F48814
WARNING: Do not disconnect USB power, press RESET/DFU, remove the SD card, or otherwise interrupt the device while CPLD programming is in progress.
7. Reconnect Mayhem Hub and verify the CPLD
After CPLD programming has completed, reconnect Mayhem Hub to the device before issuing further serial commands.
Then run:
cpld_info portapack
Verify:
CPLD IDCODE: 0x00025610
CPLD Model: AGM AG256SL100
CPLD firmware checksum: 0x20F48814
The CPLD update is now complete.
8. Test RESET and DFU
RESET
Press the RESET push button.
The PortaPack should now reset and boot normally instead of freezing.
A short visual delay before the boot sequence is normal. The LCD retains its previous screen contents while the MCU resets; the display changes once the MCU initializes the LCD again.
DFU
Test the DFU push button using current Mayhem firmware.
The DFU procedure should now operate normally without requiring USB power to be disconnected.
Results
Before the CPLD update:
CPLD checksum: 0x17DDE5B1
RESET: FAIL
DFU: FAIL
After the CPLD update:
CPLD checksum: 0x20F48814
Magic: 0x3397A006
RESET: PASS
DFU: PASS
The DFU signal was also electrically checked before and after the update.
Before the update, the released DFU signal showed an incorrect/marginal LOW level of approximately 1.1–1.2 V.
After the update, clean logic levels of approximately 0 V LOW / 3.2 V HIGH were measured, with no abnormal continuous current through R30.
Validation
This procedure was independently tested and validated on two PortaPack H2+ PCB v3.6 units, both equipped with:
AGM AG256SL100 (QFP100)
Original CPLD checksum: 0x17DDE5B1
The two PortaPacks were installed on:
- HackRF One r6
- HackRF One r9
After updating both units to CPLD checksum 0x20F48814:
- RESET works correctly.
- DFU works correctly.
- General PortaPack functionality was tested.
- No functional or RF degradation was observed.
Background
This CPLD image and programming method were previously developed and tested by Bernd Herzog and JLynx on an older H2/H2M as part of the CPLD reset fix.
See Mayhem PR #2401 for the original Bernd development/reference.
Bernd has subsequently reconfirmed that his unit still contains CPLD checksum 0x20F48814 and that RESET and DFU work correctly with current Mayhem firmware.
Additional technical investigation, oscilloscope measurements and before/after electrical results are documented in Mayhem issue #3289.
Special thanks to JLynx and Bernd Herzog for their invaluable technical support, and to ChatGPT for assisting throughout the investigation, analysis and validation process.