Hi all,



I'm looking for help/advise working with a S11108 is a CMOS linear image sensor. My son is studying computer science at university who has been helping. We are using the S11108 to scan a moving object which is a plastic tape like product that has a gap in the middle running down the length of the material. The gap changes changes size and we would like to monitor this. Please see my circuit design and arduino sketch attached. I believe the sensor is capable of doing the job. However we are doing something wrong with regards to the programming or maybe circuit design. For whatever reason we don’t seem to be getting anything on the video output line or end of signal line after S11108 sensor. Could anyone on here point me into the right direction as to what the problem may be? Any help would be much appreciated.



Regards



Christopher



Google drive link to schematic and sketch: [insert link]https://drive.google.com/drive/folders/1nIQr4zYgdKwpUESumwOak8UBdYV0fIJP?usp=drive_link

 

 

Hi Kim.
Have you an oscilloscope to check the Output at pin #13 of the S11?, if Yes, post a photo of the scope image.
It appears you are using the LM358 as a Comparator?
Is the 5Kpot a multi-turn?
E

 

hi Kim,
You do not show pin #2 ,VSS to 0V on your diagram?
E

 

hi Kim,
You do not show pin #2 ,VSS to 0V on your diagram?
E

Hello Eric,
I did in fact notice this late last night in the example diagram of the circuit and tested plugging the other VCC and VDD lines into +5V and GND respectively. I saw no difference on Pin 13 waveform but I can get a picture of my outputs and also the waves generated on the ST and CLK lines.
Regards

Christopher

 

Hey Eric,
Here’s the oscilloscope traces you asked for.
I’m pretty sure the clock wave is wrong but I’m unsure how it can be corrected with a circuit.
Also I have seen in the S11108 there are some non-inverting buffers on the incoming and outgoing signal lines from the chip. Do you know why the diagram has these buffere?

Any advice you have would be much appreciated.
Regards,
Christopher

 

Hi Kim,
Checking the video output on pin #13, the datasheet states a positive offset of 0.5V, your scope image appears to show zero?

I guess you have also tried to scope pin #13 with the pin not connected to the LM358?

Also the Clock signal seems to be swinging approx +/-2V about zero?

Can you confirm the scope centre line Xaxis is at zero and the scope is set for DC signal display?

The ST pulses look OK.
E

 

Hi Kim.
Check your rise/Fall times on the clock signal, looking at the scope image, suggests they are well out of specification.
Is your scope probe correctly trimmed?
E

 

Hi Kim,
Checking the video output on pin #13, the datasheet states a positive offset of 0.5V, your scope image appears to show zero?

I guess you have also tried to scope pin #13 with the pin not connected to the LM358?

Also the Clock signal seems to be swinging approx +/-2V about zero?

Can you confirm the scope centre line Xaxis is at zero and the scope is set for DC signal display?

The ST pulses look OK.
E

Would this 0.5v offset be present if my timings were wrong and if this isn't the case what does this absence of an offset mean?

My measurements on pin #13 were performed between the opamp and the ccd as I wanted to see what the signal looked like before the comparator circuit.

There wasn't any offsets applied to the centreline Xaxis when I made my measurements.

In regards to clock rise and fall times could this perhaps be due to me trying to get too high of a frequency out of the Arduino timer?

Regards

Christopher

 

Would this 0.5v offset be present if my timings were wrong and if this isn't the case what does this absence of an offset mean?

My measurements on pin #13 were performed between the opamp and the ccd as I wanted to see what the signal looked like before the comparator circuit.

Hi,
Disconnect pin 13 from the LM358 input, and scope pin 13.

E
Is this a College assignment project?

 

Hi,
Disconnect pin 13 from the LM358 input, and scope pin 13.

E
Is this a College assignment project?

I have scoped just pin #13 and it's got 0v output although I don't think I was clear about this in my last message.
This isn't an assignment and is more of a personal project.