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Messages - v8dave

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Customer Projects / Commercial design with 7" LCD
« on: May 02, 2016, 09:49:26 PM »
Using the NHD-7.0-800480EF-ATXV#-CTP display I built in-house, a commercial design for an international client to log data from a down hole gauge and communicate and control a Variable Speed Drive.

The Newhaven displays are excellent. They may not be the cheapest on the market compared to Chinese options but the support from Newhaven is second to none and the fact that all the voltages for the displays are generated within the LCD module makes the design simple as using 3.3V and the digital inputs. Quality is also top notch.

I have used the 4.3" and 5.0" displays in the past but decided to use the 7" on this unit to better fit the overall unit size.

The unit itself has a special interface that I designed to convert two 4-20mA sensors onto the one grounded cable. This allows me to have temperature and pressure in the well and at a price that makes it low cost enough to allow this client to instrument each well. Conventional downhole sensors are expensive. Using 4-20mA we can instrument wells down to 12,000 feet depth.

The rest of the system is standard 4-20mA inputs for surface pressure and temperature sensors and an optional storage tank calculation for one of the sensors.

The unit includes a 3G GSM modem to allow the well data to be transmitted to a server or via SMS. This modem can be offered in USA and International operating frequencies.

My only request to Newhaven for the future is to have a high brightness version of this display. Something along the lines of the 4.3" option would be great. :)

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TFTs / Re: FT5306 Touch Controller
« on: December 02, 2015, 07:50:02 PM »
I'd like to add that I am also not seeing any gestures with the controller on the 7" or the 5"

The gestures register always shows 0x00 for any left right or up down gesture. For me zoom in and out is being detected.

TFTs / LCD timing signals
« on: January 12, 2015, 09:13:52 PM »
I am using an NHD-7.0-800480EF-ATXV display with a Allwinner A20 Cortex A7 processor and I am seeing some flickering and whiteouts on the display when I run on battery power and the battery voltage gets low. The voltage to the LCD is still close to 3.3V but any current increase from the board causes small dips in the supply and this affects the stability in the LCD.

The battery is 6600mA capacity and I think the issue with the LCD is due to the fact the board design uses a buck regulator for the 3.3V instead of a buck/boost so that it can still run when the input is close to 3.3V

NOW.. What I did find during all this checking was that the LCD clock output from the CPU is not a square wave as I was expecting, based on the information in the datasheets.

This image shows that the clock is actually a sine wave. Now, when I posted about this on another group, they said to check the scope bandwidth etc. Measuring the R,G and B lines, which are clocked in at the same rate as the DCLK, they have a nice 0 to 3.3V swing and square edges so I am confident that the bandwidth is not the issue here.

As you can see, the clock is not 0 to 3.3V but approx 1V to 1.8V swing. This clock is 33Mhz.

I also checked the output from an LPC1788 driving an LCD at 25Mhz and it shows the same type of output.

The issue I think is that the voltage levels are critical at lower voltages but not so sure until I can get confirmation that the clock output from the CPU is correct.

Does anyone know if what I am seeing is indeed correct? Even looking at the controller datasheet on the LCD shows a square type clock and the triggering voltages would not be met with this clock I am seeing.

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