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CFAG320240CX-TFH-TTS read problem

hulud

New member
hi, i have a problem with this display, i'm using it in 6800 mode, but when i try to handle WR pin (pin 5 on display connector) to read from the display i doesn't work.
pin 5 on the connector is shorted with GND (on the pcb i suppose), and so i cannot drive it.

is this an hardware limitation? on the back of the display i can see 320240CX rev. D.

Thanks
Andrea
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when i try to handle WR pin (pin 5 on display connector) to read from the display i doesn't work. pin 5 on the connector is shorted with GND (on the pcb i suppose), and so i cannot drive it.
This is abnormal. Have you checked for shorts in your wiring? If you disconnect pin 5 from your wiring, and put a pullup (10K ohm) to +5, and the pin still is at 0v, then I'd think the display is defective.
 

hulud

New member
Even without my connector i can see that pin 5 and 1 are shorted, there are 22 ohms between.
PCB wiring of pin 5 seems straight to the connector, but maybe there is something under epson S1D13700.
If i try to set pin5 (i'm using 3.3v signals) i see on my oscilloscope that the output goes 2v instead of 3.3v
 

CF Support2

Administrator
As shipped, the CFAG320240CX series is a +5v module. With some modification they can be configured for +3.3v operation. The Epson controller is 3.3v tolerant, but there is supporting circuitry that needs to be changed to fully support this.
 
... i can see that pin 5 and 1 are shorted, there are 22 ohms between.
That seems very wrong. Compare pins 4 and 6 to ground, and see if they are also low resistance. If not, I suspect the pin 5 input is damaged.

Afterthought: try reversing your ohmmeter leads, as you have a 50/50 chance of turning on an input protection diode.

It is surprising that your cpu can deliver 2 volts into 22 ohms (that is 91 mA!). The display should work with 3.3 v logic inputs, so you should probably request a replacement under warranty.
 
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