ESP8266
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TODO: add notes
Pin numbers written on the board itself do not correspond to ESP8266 GPIO pin numbers. Constants are defined to make using this board easier:
If you want to use NodeMCU pin 5, use D5 for pin number, and it will be translated to 'real' GPIO pin 14.
This module is sold under many names for around $6.50 on AliExpress and it's one of the cheapest, fully integrated ESP8266 solutions.
It's an open hardware design with an ESP-12E core and 4 MB of SPI flash.
Acording to the manufacturer, "with a micro USB cable, you can connect NodeMCU devkit to your laptop and flash it without any trouble". This is more or less true: the board comes with a CP2102 onboard USB to serial adapter which just works, well, the majority of the time. Sometimes flashing fails and you have to reset the board by holding down FLASH + RST, then releasing FLASH, then releasing RST. This forces the CP2102 device to power cycle and to be re-numbered by Linux.
The board also features a NCP1117 voltage regulator, a blue LED on GPIO16 and a 220k/100k Ohm voltage divider on the ADC input pin.
Full pinout and PDF schematics can be found here
This board comes with 2 MB of SPI flash and optional accessories (e.g. evaluation board ESP8266-EVB or BAT-BOX for batteries).
The basic module has three solder jumpers that allow you to switch the operating mode between SDIO, UART and FLASH.
The board is shipped for FLASH operation mode, with jumpers TD0JP=0, IO0JP=1, IO2JP=1.
Since jumper IO0JP is tied to GPIO0, which is PIN 21, you'll have to ground it before programming with a USB to serial adapter and reset the board by power cycling it.
UART pins for programming and serial I/O are GPIO1 (TXD, pin 3) and GPIO3 (RXD, pin 4).
Get the board schematics here
This is a stripped down version of the above. Behaves identically in terms of jumpers but has less pins readily available for I/O. Still 2 MB of SPI flash.
Product page: https://www.sparkfun.com/products/13231
TODO: add notes
TODO: add notes
ESPino integrates the ESP-12 module with a 3.3v regulator, CP2104 USB-Serial bridge and a micro USB connector for easy programming. It is designed for fitting in a breadboard and has an RGB Led and two buttons for easy prototyping.
For more information about the hardware, pinout diagram and programming procedures, please see the datasheet.
Product page: http://www.espino.io/en
WifInfo integrates the ESP-12 or ESP-07+Ext antenna module with a 3.3v regulator and the hardware to be able to measure French telemetry issue from ERDF powering meter serial output. It has a USB connector for powering, an RGB WS2812 Led, 4 pins I2C connector to fit OLED or sensor, and two buttons + FTDI connector and auto reset feature.
For more information, please see WifInfo related blog entries, github and community forum.
These modules come in different form factors and pinouts. See the page at ESP8266 community wiki for more info: ESP8266 Module Family.
Usually these modules have no bootstapping resistors on board, insufficient decoupling capacitors, no voltage regulator, no reset circuit, and no USB-serial adapter. This makes using them somewhat tricky, compared to development boards which add these features.
In order to use these modules, make sure to observe the following:
There are many different USB to Serial adapters / boards. To be able to put ESP8266 into bootloader mode using serial handshaking lines, you need the adapter which breaks out RTS and DTR outputs. CTS and DSR are not useful for upload (they are inputs). Make sure the adapter can work with 3.3V IO voltage: it should have a jumper or a switch to select between 5V and 3.3V, or be marked as 3.3V only.
Adapters based around the following ICs should work:
PL2303-based adapters are known not to work on Mac OS X. See https://github.com/igrr/esptool-ck/issues/9 for more info.
PIN | Resistor | Serial Adapter |
---|---|---|
VCC | VCC (3.3V) | |
GND | GND | |
TX or GPIO2* | RX | |
RX | TX | |
GPIO0 | PullUp | DTR |
Reset* | PullUp | RTS |
GPIO15* | PullDown | |
CH_PD | PullUp |
ESPxx Hardware
PIN | Resistor | Serial Adapter |
---|---|---|
VCC | VCC (3.3V) | |
GND | GND | |
TX or GPIO2 | RX | |
RX | TX | |
GPIO0 | GND | |
Reset | RTS* | |
GPIO15 | PullDown | |
CH_PD | PullUp |
ESPxx Hardware
PIN | Resistor | Power supply |
---|---|---|
VCC | VCC (3.3V) | |
GND | GND | |
GPIO0 | PullUp | |
GPIO15 | PullDown | |
CH_PD | PullUp |
The ESP module checks at every boot the Pins 0, 2 and 15. based on them its boots in different modes:
GPIO15 | GPIO0 | GPIO2 | Mode |
---|---|---|---|
0V | 0V | 3.3V | Uart Bootloader |
0V | 3.3V | 3.3V | Boot sketch (SPI flash) |
3.3V | x | x | SDIO mode (not used for Arduino) |
at startup the ESP prints out the current boot mode example:
note:
Number | Description |
---|---|
0 | unknown |
1 | normal boot |
2 | reset pin |
3 | software reset |
4 | watchdog reset |
the first value respects the pin setup of the Pins 0, 2 and 15.
Number | GPIO15 | GPIO0 | GPIO2 | Mode |
---|---|---|---|---|
0 | 0V | 0V | 0V | Not valid |
1 | 0V | 0V | 3.3V | Uart |
2 | 0V | 3.3V | 0V | Not valid |
3 | 0V | 3.3V | 3.3V | Flash |
4 | 3.3V | 0V | 0V | SDIO |
5 | 3.3V | 0V | 3.3V | SDIO |
6 | 3.3V | 3.3V | 0V | SDIO |
7 | 3.3V | 3.3V | 3.3V | SDIO |
note:
Product page: http://wemos.cc
Product page: http://wemos.cc