ESP8266 Community Forum

- Sun Jan 03, 2016 12:18 am #37754 I2C from what I can tell only needs 1 SDA and 1 SCL pin serial data and serial clock...

Why not use SD2 and SD3 as GPIO while still leaving the ability for I2C communications?



Just a thought being that the LUA firmware does it.

EDIT UPDATE!!!!!!!!!!!!!!!!!!!!!! BELOW...
I believe the data lines are not for I2C they are for SD card slot DUH!

Code: Select allGPIO's USED BASIC/LUA
GPIO- Used For Basic / Used For LUA this is the format of the table:
GPIO 0- Used for Both
GPIO 1- Used for Both
GPIO 2- Used for Both
GPIO 3- Used for Both
GPIO 4- Used for Both
GPIO 5- Used for Both
GPIO 6- NOT Used for Both
GPIO 7- NOT Used for Both
GPIO 8- NOT Used for Both
GPIO 9- Used On LUA Only
GPIO 10- Used On LUA Only
GPIO 11- NOT Used for Both
GPIO 12- Used for Both
GPIO 13- Used for Both
GPIO 14- Used for Both
GPIO 15- Used for Both
GPIO 16- Used for Both
ADC0 A0- Used Only For Basic <---- This may be incorrect but technically it is not a GPIO!


Couple extra GPIO's would always be handy.

-forlotto

Last edited by forlotto on Mon Jan 04, 2016 12:04 am, edited 3 times in total.

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- Sun Jan 03, 2016 9:54 am #37776 I'm not sure, but isn't the I2C done in software (bitbanged)? If so, why isn't the hardware I2C native to the esp8266 used for I2C?

- Sun Jan 03, 2016 11:39 am #37781 I have generally been flowing the arduino projects lead for such things.

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- Sun Jan 03, 2016 1:01 pm #37788

why isn't the hardware I2C native to the esp8266 used for I2C?

There is no hardware I2C on ESP866, even if Espressif mentioned I2C in their specs, they never mentioned it has an hardware implementation, and their SDK doesn't provide anything about it.

EDIT : I was partially wrong, there are some register address definitions, but nothing else, undocumented, so no body use them yet.

From sdk/ld/eagle.rom.addr.v6.ld

Code: Select allrom_i2c_readReg = 0x40007268;
rom_i2c_readReg_Mask = 0x4000729c;
rom_i2c_writeReg = 0x400072d8;
rom_i2c_writeReg_Mask = 0x4000730c;