Issue with I2c address

[samehhady]

Hello, first of all thank you for your work.

I am having issues tho, I have it all compiled and flashed to my ESP but I am not able to show anything on my screen.

I am only using 1 screen which is Chinese SSD1306 version.

http://www.aliexpress.com/item/Free-shipping-1Pcs-128X64-OLED-LCD-LED-Display-Module-For-Arduino-0-96-I2C-IIC-SPI/2036109567.html

I have updated the i2c.c & ssd1306_i2c.c as you mentioned and changed the pins ( I am using pin 2 & 14 )

When I press init i get failed message & by debugging it seems failing in the i2c_write(ctx->address) part as it seems always coming with false.

Do i have to change this address based on my oled? 0x3c, 0x3d, etc

Can you please help me in figuring out this issue.

Thanks.
Sameh

[baoshi]

Well there are many things can go wrong. Let me try to explain.
First, the screen you linked said "for Arduino". Arduino usually uses 5V I/O, but ESP8266 uses 3.3V. You can check if there is a series resistor on SCL and SDA pin. If there is, it should be shorted.
Secondly, please check if the screen module has builtin pull-up resistor on I2C bus.
Above are hardware issues. If you have a oscilloscope or a logic analyzer these will be easy to diagnose.
Then, for software issues, there are some 0.96in Oled screens that are using SH1106 controller instead of SSD1306. I do not know how to differentiate them but the instruction sets are different.
One more possibility is the I2C address, I see there is a jumper on the module labeled address. It should be 1-3D and 0-3C.
Finally you may check the initialization code for GPIO 2 and 14, you may post your code and I can have a try.

cheers

Baoshi

[samehhady]

Baoshi,

Thank you for your detailed reply.

Well my screen can work with both 3.3v & 5v, I've tested it on Arduino ( 3.3v ) and it worked perfectly with the U8glib library, and from this library I knew it is the ssd1306 version.

One other test that I did is to try another code for lua which works for ssd1306 & it worked directly beside the idea that is it very simple demo but at least I saw something on my screen. I was using the same 2 pins on the lua script.
http://www.esp8266.com/viewtopic.php?f=24&t=1318&hilit=ssd1306#p7747

So I guess my screen is fine and no need for resistor or shortening anything?

I've tried your code as it is and just modified the pin part and change it to:

i2c.c:

//! @brief GPIO MUX for SDA pin
#define SDA_MUX PERIPHS_IO_MUX_GPIO2_U
//! @brief GPIO FUNC for SDA pin
#define SDA_FUNC FUNC_GPIO2
//! @brief GPIO pin location for SDA pin
#define SDA_PIN 2
//! @brief GPIO bit location for SDA pin
#define SDA_BIT BIT2

//! @brief GPIO MUX for SCL pin
#define SCL_MUX PERIPHS_IO_MUX_MTMS_U
//! @brief GPIO FUNC for SCL pin
#define SCL_FUNC FUNC_GPIO14
//! @brief GPIO pin location for SCL pin
#define SCL_PIN 14
//! @brief GPIO bit location for SCL pin
#define SCL_BIT BIT14

ssd1306_i2c.c:

#define PANEL0_TYPE SSD1306_NONE
//! @brief I2C address for panel 0
#define PANEL0_ADDR (0x3c << 1)
//! @brief If panel 0 has external RESET pin, define this as 1
#define PANEL0_USE_RST 1
//! @brief GPIO MUX for panel 0 RESET pin
#define PANEL0_RST_MUX PERIPHS_IO_MUX_GPIO2_U
//! @brief GPIO FUNC for panel 0 RESET pin
#define PANEL0_RST_FUNC FUNC_GPIO2
//! @brief GPIO bit location for panel 0 RESET pin
#define PANEL0_RST_BIT BIT2

//! @brief Panel 1 type, define to SSD1306_NONE if not used.
#define PANEL1_PANEL_TYPE SSD1306_128x64
//! @brief I2C address for panel 1
#define PANEL1_ADDR (0x3C << 1)
//! @brief If panel 1 has external RESET pin, define this as 1
#define PANEL1_USE_RST 0
//! @brief GPIO MUX for panel 1 RESET pin
#define PANEL1_RST_MUX PERIPHS_IO_MUX_MTMS_U
//! @brief GPIO FUNC for panel 1 RESET pin
#define PANEL1_RST_FUNC FUNC_GPIO14
//! @brief GPIO bit location for panel 1 RESET pin
#define PANEL1_RST_BIT BIT14

and in the init method in the shell file i removed the first screen and only checking ssd1306_init(1)

[baoshi]

Hi,
I just tried your code and pin configuration and if works nicely, except mine screen address is 0x3D. You may try both addresses see if it works.
Cheers,
Baoshi