Author Topic: RS232 not working  (Read 135 times)

miles

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RS232 not working
« on: March 06, 2019, 08:59:09 PM »
I just unwrapped a NHD-0216K3Z-FL-GBW-V3. It's hooked up via RS232 to a USB to serial adapter and then to my computer.

I can connect to the COM port via realterm or putty and send the display whatever I want but it doesn't seem to parse it correctly. For example, sending it 0-00 produces a bunch of hieroglyphics.

What am I missing? I'm sure it's something quite simple.

The jumpers on the back are both open.

RS232 in is hooked up to pin 1 on the 3 pin plug. Power is on pins 2 and 3 on the same plug. RS232 ground is on pin 5 on the 6 pin plug.

 

Ted_M

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Re: RS232 not working
« Reply #1 on: March 07, 2019, 09:34:59 AM »
Hi Miles,

The RS-232 signal must be 5V TTL compatible. Communication format is 8-bit data, 1 Stop bit, no parity, no hand-shaking.
The default BAUD rate set for the display is 9600, and is changeable with a command function. Once the command to change the BAUD rate has been accepted, it will be saved in the display module memory for future communications.
To change the default BAUD rate of the display, see page 8 of the datasheet. http://www.newhavendisplay.com/specs/NHD-0216K3Z-FL-GBW-V3.pdf
Once the default speed has been changed, disconnect communications and reconnect at the new BAUD rate.

Best Regards,

miles

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Re: RS232 not working
« Reply #2 on: March 07, 2019, 10:56:29 AM »
Hi Ted,

I can select 8 bit, 1 stop bit parity and handshaking in RealTerm. I can also select BAUD Rate. 9600 is perfectly fine for my application so I don't have any need to change it.


When I hook an oscilloscope up to the RS232 feed (ground to ground and measure to the Rx), it sits around 0 until I try sending a packet via RealTerm. At that point it'll trigger the scope and the voltage will go to ~5v. As far as I know, this discribes 5V TTL.

Any further thoughts?

Miles

Ted_M

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Re: RS232 not working
« Reply #3 on: March 07, 2019, 11:39:51 AM »
Hi Miles,

The display will need to be initialized and programmed to print characters to the display. 
Please refer to the example code http://www.newhavendisplay.com/app_notes/Serial_LCD.txt  to help you get started.

Best Regards,




 

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