Hi Staff
Question
ADC128D818 may not respond to I2C access.
We believe that there are no particular problems with the SDA and SCL signal timing and waveforms.
・ SDA and SCL pull-up resistors are 5kΩ (Vcc = 3.3V)
・ 100kbps, rise time 0.9us.
・ SDA changes at the same time as the SCL falls, and the stable level of the SDA at the start of the SCL is read.
-NAK (High) is returned for write access to address 1D of this device. Inaccessible!
As a countermeasure,
if you connect CR (33k ohm + 2200pF) to SCL and connect it to GND,
normal operation will occur and NAK (Low) will be returned.
There is no difference in the signal waveform before and after connecting CR to SCL (check with an oscilloscope)
What is the reason why I2C does not work properly without connecting CR?
please tell me.
best regards
cafain