- Wed Feb 18, 2015 3:58 pm
#10119
And just as a general note: Even most or all GPIOs of the ESP have internal pull-ups, those pull-ups are only active at the earliest after the chip is fully powered up. If the pin is used for a startup function (defined state at reset or power-up) and in particular if that pin is evaluated very early on (e.g. by hardware) you should pull it externally to a defined state. And GPIO2 apparently has some startup function, intentionally (maybe for QA/testing) or unintentionally.
- Thu Feb 19, 2015 10:54 am
#10155
Definitely.
Looking at the Espressif reference schematic, they leave GPIO2 not connected. But another note refers to the strapping page: UOTXD,MTDO,GPIO0,GPIO2 might affect the bootmode. So it is documented...
Makes me wonder if there is a register that can set a "permanent" pullup on that pin, like some of the others.
24 hours in, I have 2 ESP-01s running on 60 seconds sleep/wake cycles with no disruption. Looks like pulling up GPIO2 nailed it. One has 10K, the other has 4.7K (which is actually the reference requirement of the DS18B20 - I had assumed it was in the sealed unit I was using - it wasn't
). When I think about it, the 2 meter cable attached to the DS18B20 on GPIO2 would make a good antenna for noise. I am surprised it was as stable as it was without the pullup.
Here is the strapping page:
U0TXD Strapping to chip_test_mode 1: normal mode; 0: chip_test_mode
MTDO Strapping to STRAPPING_GPIO2 for SW boot_sel [2]
GPIO0 Strapping to STRAPPING_GPIO1 for SW boot_sel [1]
GPIO2 Strapping to STRAPPING_GPIO0 for SW boot_sel [0]
SD_DATA3 Strapping to STRAPPING_GPIO[15] for SW sdio_boot_sel [2]
SD_DATA2 Strapping to STRAPPING_GPIO[14] for SW sdio_boot_sel [1]
SD_DATA0 Strapping to STRAPPING_GPIO[13] for SW sdio_boot_sel [0]
Boot_sel SD_sel != 3'b010 SD_sel == 3'b010
7 SDIO HighSpeed V2 IO Uart1 Booting
6 SDIO LowSpeed V1 IO Uart1 Booting
5 SDIO HighSpeed V1 IO Uart1 Booting
4 SDIO LowSpeed V2 IO Uart1 Booting
3 FLASH BOOT
2 Jump Boot
1 UART Boot
0 Remapping
GPIO0 after reset, the default is function5 to export the clock
GPIO2 U0TXD signal can be output through GPIO2 pad besides U0TXD pad
epsoc wrote:And just as a general note: Even most or all GPIOs of the ESP have internal pull-ups, those pull-ups are only active at the earliest after the chip is fully powered up. If the pin is used for a startup function (defined state at reset or power-up) and in particular if that pin is evaluated very early on (e.g. by hardware) you should pull it externally to a defined state. And GPIO2 apparently has some startup function, intentionally (maybe for QA/testing) or unintentionally.
Definitely.
Looking at the Espressif reference schematic, they leave GPIO2 not connected. But another note refers to the strapping page: UOTXD,MTDO,GPIO0,GPIO2 might affect the bootmode. So it is documented...
Makes me wonder if there is a register that can set a "permanent" pullup on that pin, like some of the others.
24 hours in, I have 2 ESP-01s running on 60 seconds sleep/wake cycles with no disruption. Looks like pulling up GPIO2 nailed it. One has 10K, the other has 4.7K (which is actually the reference requirement of the DS18B20 - I had assumed it was in the sealed unit I was using - it wasn't
). When I think about it, the 2 meter cable attached to the DS18B20 on GPIO2 would make a good antenna for noise. I am surprised it was as stable as it was without the pullup.Here is the strapping page:
U0TXD Strapping to chip_test_mode 1: normal mode; 0: chip_test_mode
MTDO Strapping to STRAPPING_GPIO2 for SW boot_sel [2]
GPIO0 Strapping to STRAPPING_GPIO1 for SW boot_sel [1]
GPIO2 Strapping to STRAPPING_GPIO0 for SW boot_sel [0]
SD_DATA3 Strapping to STRAPPING_GPIO[15] for SW sdio_boot_sel [2]
SD_DATA2 Strapping to STRAPPING_GPIO[14] for SW sdio_boot_sel [1]
SD_DATA0 Strapping to STRAPPING_GPIO[13] for SW sdio_boot_sel [0]
Boot_sel SD_sel != 3'b010 SD_sel == 3'b010
7 SDIO HighSpeed V2 IO Uart1 Booting
6 SDIO LowSpeed V1 IO Uart1 Booting
5 SDIO HighSpeed V1 IO Uart1 Booting
4 SDIO LowSpeed V2 IO Uart1 Booting
3 FLASH BOOT
2 Jump Boot
1 UART Boot
0 Remapping
GPIO0 after reset, the default is function5 to export the clock
GPIO2 U0TXD signal can be output through GPIO2 pad besides U0TXD pad
ESP8266 for dummies, LuaLoader and project updates: http://benlo.com/esp8266
- Fri Feb 20, 2015 3:13 am
#10200
This module from OLIMEX https://www.olimex.com/Products/IoT/MOD ... P8266-DEV/ has 2k pull-ups on GPIO0, GPIO2, and MTDO. See the schematic here: https://www.olimex.com/Products/IoT/MOD ... ematic.pdf
- Fri Feb 20, 2015 4:49 am
#10209
i wonder one thing. if zombie mode coming with gpio2 state, how i can use modified at21 example without any zombie mode?
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Lets get the party started and +1
[url=https://www.banggood.com/custlink/KvGGhGF4wG[/url]
I like ESP8266 and ESP8285 and ESP32
