ESP32 Forum

Posted: **Mon Jan 18, 2021 7:08 pm**

Does anyone know why my `erase_flash` is not working? I just run the command idf.py -p /dev/tty.usbserial-AB0JNMBP erase_flash and even though it says Chip erase completed successfully it just reboots to the old program.

Btw, I'm using a custom partition table as below for my OTA feature.

I have 16MB of flash and I'm using ESP IDF V4.2

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# Name,   Type, SubType, Offset,   Size, Flags
nvs,      data, nvs,     ,        0x4000,
otadata,  data, ota,     ,        0x2000,
phy_init, data, phy,     ,        0x1000,
factory,  app,  factory, ,        4M,
ota_0,    app,  ota_0,   ,        4M,
ota_1,    app,  ota_1,   ,        4M,
coredump, data, coredump,,	  64K

Below is the console output,

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$ idf.py -p /dev/tty.usbserial-AB0JNMBP erase_flash
WARNING: Support for Python 2 is deprecated and will be removed in future versions.
Executing action: erase_flash
Running esptool.py in directory /Users/Prasad/build
Executing "/Users/Prasad/.espressif/python_env/idf4.3_py2.7_env/bin/python /Users/Prasad/esp/esp-idf/components/esptool_py/esptool/esptool.py -p /dev/tty.usbserial-AB0JNMBP -b 460800 --before default_reset --after hard_reset --chip esp32 erase_flash"...
esptool.py v3.1-dev
Serial port /dev/tty.usbserial-AB0JNMBP
Connecting....
Chip is ESP32-D0WDQ6 (revision 1)
Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, Coding Scheme None
Crystal is 40MHz
MAC: 30:ae:a4:f3:a5:c8
Uploading stub...
Running stub...
Stub running...
Changing baud rate to 460800
Changed.
Erasing flash (this may take a while)...
Chip erase completed successfully in 0.0s
Hard resetting via RTS pin...
Done

Posted: **Tue Jan 19, 2021 1:42 am**

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Chip erase completed successfully in 0.0s

That is awfully fast for a full erase... that normally takes tens of seconds, depending on the flash chip. What hardware are you using?

Posted: **Tue Jan 19, 2021 7:57 am**

Indeed it definitely can’t be erased in 0.0 seconds. This is custom hardware I did for one of our client’s product. It still runs fine except I cannot update the firmware with OTA or via serial. It downloads the new firmware but reboots to the factory version. Then I thought that the flash might be corrupted and I tried to erase the entire flash but it doesn’t erase the flash. Also, I tried the official flash download tool as well, which also says erase success but restart to the factory firmware. Do you think this might be due to a defective flash chip? I don’t have a spare flash chip with me but I ordered to try that out too.

Posted: **Wed Jan 20, 2021 5:40 am**

I know that most flash chips have configuration registers that can write-protect some or all of the flash memory. You can read those registers using 'esptoool.py read_flash_status'. Perhaps if you compare the results of that to the datasheet of whatever flash chip you use, that may lead to the reason why this is happening?

Posted: **Wed Jan 20, 2021 12:37 pm**

I'm using the GD25Q127 flash chip from GigaDevice and I checked the 'esptool.py read_flash_status --bytes 3' and it gave me '0x4000fe' Which is 010000000000000011111110 and the last two bits are Write Enable Latch and Write in Progress respectively. According to the datasheet(Page #14 attached), if the Write Enable Latch is 1 then you can write to the chip and it can accept erase command. So essentially this chip is not write protected. Am I reading this correctly?

Posted: **Wed Jan 20, 2021 4:47 pm**

The Chip Erase (CE) command is executed, only if the Block Protect (BP2, BP1, and BP0) bits are 0 and CMP=0 or the Block Protect
(BP2, BP1, and BP0) bits are 1 and CMP=1.

Posted: **Fri Jan 22, 2021 7:13 am**

You are right @WiFive. I missed that in the datasheet. Thanks for pointing that out. I wonder how that happened as I haven't purposely change any of the status register values before. Anyway, My new flash chips arrived and I just tested and it works fine. I checked 'esptool.py read_flash_status --bytes 3' and returned '0x400002' which is '010000000000000000000010' and writable according to the datasheet. Above BP2, BP1, and BP0 bits are 0, and WEL(Write Enable Latch) is 1.

: WEL.png (3.31 KiB) Viewed 15620 times

: status register.png (22.06 KiB) Viewed 15620 times

Thanks @ESP_Sprite for pointing out the 'read_flash_status', which I didn't know existed within esptool

Posted: **Fri Jan 22, 2021 8:25 am**

Hi Prasad,

It's also possible to write_flash_status, so depending on the exact command set of the flash chip it may be possible to clear those write-protect bits.

(Hopefully not, but on the offchance it happens to re-enable itself again after being cleared, check your hardware design for any signal integrity problems that might be causing a SPI command to be corrupted.)

Posted: **Mon Jan 25, 2021 8:11 am**

Hi Angus, I have desoldered the old flash chip from my PCB. But I will definitely give it a shot and let you know. Thanks.

Posted: **Fri Feb 05, 2021 7:08 pm**

Hi Angus, I have successfully cleared the write protected bits using 'esptool.py write_flash_status --bytes 2 --non-volatile 0'. Now I can write to and read from that chip again.

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idf.py erase_flash doesn't work

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