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idf.py erase_flash doesn't work

Posted: Mon Jan 18, 2021 7:08 pm
by Prasad
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

Re: idf.py erase_flash doesn't work

Posted: Tue Jan 19, 2021 1:42 am
by ESP_Sprite

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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?

Re: idf.py erase_flash doesn't work

Posted: Tue Jan 19, 2021 7:57 am
by Prasad
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.

Re: idf.py erase_flash doesn't work

Posted: Wed Jan 20, 2021 5:40 am
by ESP_Sprite
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?

Re: idf.py erase_flash doesn't work

Posted: Wed Jan 20, 2021 12:37 pm
by Prasad
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?

Re: idf.py erase_flash doesn't work

Posted: Wed Jan 20, 2021 4:47 pm
by WiFive
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.

Re: idf.py erase_flash doesn't work

Posted: Fri Jan 22, 2021 7:13 am
by Prasad
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
WEL.png (3.31 KiB) Viewed 15320 times
status register.png
status register.png (22.06 KiB) Viewed 15320 times

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

Re: idf.py erase_flash doesn't work

Posted: Fri Jan 22, 2021 8:25 am
by ESP_Angus
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.)

Re: idf.py erase_flash doesn't work

Posted: Mon Jan 25, 2021 8:11 am
by Prasad
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.

Re: idf.py erase_flash doesn't work

Posted: Fri Feb 05, 2021 7:08 pm
by Prasad
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.