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Forum Index : Microcontroller and PC projects : Flashing ESP8266’s
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| Phil23 Guru  Joined: 27/03/2016 Location: AustraliaPosts: 1664 |
Hi All, One for the experts. I've previously flashed an ESP8266 as per this post. With regards to GPIO0; Does it need to be held low for the entire flashing process, or is GPIO0 low only required on reset/powerup? Reason I ask is I have this board:- 
The two switches on it pull Reset & GPIO0 low. It seems unfeasible to be holding the GPIO button down for the entire flashing process. Just doesn't make sense to have a momentary switch if in reality a latching one is required. Holding it down while pressing the reset "Seems" to result in successful flashing, according to the flash logs. BUT, and may be a separate issue; Last night the one I've been using went into a state of constantly flashing the Blue LED on power up. Even after what appears to be successful flashes nothing changes. Haven't tried a new ESP8266 yet. Thanks Phil |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1664 |
Update:- Just tried flashing an unused ESP8266 with this board & all went successfully. Seems GPIO0 only needs to be held low on reset to enable programming mode. Also my original module now seems unrecoverable. Cheers. |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9082 |
Most devices with buttons like that only require that you hold the button down at power-up. Geoff's bootloader for the Maximite series was exactly the same. This is cos one of the very first things that the code does, is check to see if that I/O(button) is low(down) or not. If it is, the code loops to the bootloader or the configuration parts of the code, and essentially ignores the button on that I/O pin from that point onwards. I am not currently aware of ANY product or device that requires you hold the update/bootload I/O or button down(or pin high or low depending on how the pin is setup), as it would be far to easy for input from that button to corrupt any updates etc, if you let go of it during updating. ...to say nothing at all of just how annoying that would be if you had to do it!  Smoke makes things work. When the smoke gets out, it stops! |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1664 |
That's why I figured GPIO0 only need to be low on start-up, as opposed to constantly low as many examples indicate. [Quote]...to say nothing at all of just how annoying that would be if you had to do it!
[/quote] That was exactly my thoughts when that board arrived. "Surely you don't need to hold that button down for 5 minutes....". Training wheels here remember. Cheers. |
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| MikeO Senior Member  Joined: 11/09/2011 Location: AustraliaPosts: 275 |
Phil, I have had this situation as you describe, I am sure this means the SPI ram has got into an unknown state and if you have not already tried, I suggest that you try the format procedure as provided as part of the ESP Basic flasher. I have also on several occasions used the NodeMCU flasher to flash the esp8266 with say, ESP-Link, started up the ESP8266 proved it worked ok , set it to some known IP address, this has usually sorted things out. Mike Codenquilts |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1664 |
Thanks Mike, Will give that a try again. Was pretty sure I did format it this morning, but I was in a hurry. Did successfully flash another one with ESP-Link though, just haven't put it to use yet. Can access & configure it by the web interface so it's good to go. The first one has some sort of activity happening though, as there is the odd straight that's recognisable in the junk it spits out when connected to a usb interface. Cheers Phil. |
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