Low Frame rate on Touchscreen

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
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gordon
Posts: 27
Joined: Sun Jan 21, 2018 6:52 pm

Low Frame rate on Touchscreen

Post by gordon » Tue Aug 14, 2018 8:41 am

Hi,

I suspect that this question might have come up before and, if so, I apologise. I have almost completed my second Portsdown and decided to give it a quick test, video only, no RF. The RPi is the older version 3 running an early version of the Stretch Software. The display is the usual 3 inch waveshare.The camera is the latest RPi cam. but fitted with a 0.5Metre lead. (ribbon).I can see the cam's output on the touchscreen, its fine as a static picture but useless when there is any movement, the frame rate appears to be very slow, less than 10 frames per second I would guess and accompanied by what almost looks like hum bars but thats probably just the low refresh rate. The voltage on the RPi is 5.2V, obtained from a Buck regulator unit. I have not yet had an opportunity to view the picture on the RF receiver and, perhaps what I am seeing is normal. Any comments please?

Gordon (G3ZYL)

G8GKQ
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Re: Low Frame rate on Touchscreen

Post by G8GKQ » Tue Aug 14, 2018 9:24 am

Hi Gordon

The refresh rate on the 3.5 inch touchscreen is only about 3 or 4 frames per second. So it sounds like what you are seeing is perfectly normal. The transmitted picture is (normally) smooth.

Dave

gordon
Posts: 27
Joined: Sun Jan 21, 2018 6:52 pm

Re: Low Frame rate on Touchscreen

Post by gordon » Tue Aug 14, 2018 5:43 pm

Hi Dave,

Many thanks for your helpful reply; I can now stop worrying. I have, in fact, now been able to confirm that the composite video output is fine. The 4-way socket on the RPi does seem to be wired in a peculiar manner but I expect there is a good reason for that.

Gordon

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