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Altera_Forum
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12 years ago

Getting data from a rtc device through I2C

Hi all, I would like to retrieve information from a RTC device which is directly connected to a GPIO, using the i2c protocol. So, the first step was to load the i2c-gpio driver with this piece ...
Altera_Forum's avatar
Altera_Forum
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12 years ago

Hello,

--- Quote Start ---

At first, please check the resistor's value, soldering of SDA line, m41t83's power line. And check the rising and falling time of SCL. It must be < 300ns. Please refer

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/cd00127116.pdf

at pp.53.

--- Quote End ---

Everything is okay, I checked all timing specifications at pp.53. However, the SCL's frequency is never higher than 12kHz, even if I set the struct i2c_gpio_platform_data's udelay field (in the linux module) to 2 for example. Normally, the SCL's frequency should be 500kHz when setting udelay to 2. Anyway, even at 12kHz, the RTC device should acknowledged to I2C frames.

So I think I am going to try with the opencore's GPIO..

jrm