On-Board Serial Port (UART/RS232)

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User avatar
hamzaazeem
Posts: 1
Joined: Tue Oct 04, 2016 11:38 am

Tue Oct 04, 2016 11:46 am

Is there any serial port, either UART or RS232, available which is directly connected to the processor ? I couldn't find any information related to serial port in the documentation. I need to connect an external microcontroller with LattePanda using direct serial port.

User avatar
phil
Posts: 1
Joined: Sat Oct 29, 2016 10:04 am

Sun Oct 30, 2016 12:17 am

I am also interested in connecting an external serial device to the LattePanda for an extisting Windows software package. In Windows Device Manager the following are listed under Ports:
Communications Port (COM1)
USB Serial Device (COM3)

From the docs page in Hardware & Accessories, Inputs and Outputs, it says "Pinouts in area U1 are assigned to the X-Z8300 core", so I have assumed I need to connect my device to the U1 block as shown on this diagram http://www.lattepanda.com/wp-content/up ... upport.png.

I connected my device to pins 9, 6, 8, in U1, and was expecting to be able to communicate with COM1, but I was not able to communicate with the device.

Can somebody please confirm which pins to use to connect to use the COM1 port that appears in Windows? Is there further configuration required first?

Thanks.

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Lutz
Posts: 214
Joined: Mon Apr 18, 2016 4:30 am
Location: Germany, NRW

Sun Oct 30, 2016 7:27 am

Voltage level on these pins is only 1.8V (digital) !
For RS232 you will need additional circuit which produce "normal" RS232 level.
https://www.maximintegrated.com/en/prod ... X3218.html will do that.

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Lutz
Posts: 214
Joined: Mon Apr 18, 2016 4:30 am
Location: Germany, NRW

Fri Nov 11, 2016 3:56 pm

@LattePanda team
Please verify the pins at "Pinouts in area U1 are assigned to the X-Z8300 core." in
http://www.lattepanda.com/docs/#Inputs_and_Outputs

I tried to use the COM1 but at least I found signal "TxD" at pin 7 (NOT pin 6!) and signal "RXD" at pin 5 (NOT pin 8!).
Now I am not happy, because of my useless pcb layout... :cry: :evil:

Using a level shifter (MAX3373) and a RS485-Transciever with Auto-Direction (MAX13488) is working... when you use the right pins.

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craftsman1234
Posts: 4
Joined: Tue Oct 18, 2016 5:08 pm

Fri Nov 25, 2016 10:23 pm

Lodin_Erikson wrote:@LattePanda team
Please verify the pins at "Pinouts in area U1 are assigned to the X-Z8300 core." in
http://www.lattepanda.com/docs/#Inputs_and_Outputs

I tried to use the COM1 but at least I found signal "TxD" at pin 7 (NOT pin 6!) and signal "RXD" at pin 5 (NOT pin 8!).
Now I am not happy, because of my useless pcb layout... :cry: :evil:

Using a level shifter (MAX3373) and a RS485-Transciever with Auto-Direction (MAX13488) is working... when you use the right pins.
So once you changed the locations of the pins U1 did COM1 port then work under windows10?

User avatar
Lutz
Posts: 214
Joined: Mon Apr 18, 2016 4:30 am
Location: Germany, NRW

Sat Nov 26, 2016 10:31 am

craftsman1234 wrote:
Lodin_Erikson wrote:@LattePanda team
Please verify the pins at "Pinouts in area U1 are assigned to the X-Z8300 core." in
http://www.lattepanda.com/docs/#Inputs_and_Outputs

I tried to use the COM1 but at least I found signal "TxD" at pin 7 (NOT pin 6!) and signal "RXD" at pin 5 (NOT pin 8!).
Now I am not happy, because of my useless pcb layout... :cry: :evil:

Using a level shifter (MAX3373) and a RS485-Transciever with Auto-Direction (MAX13488) is working... when you use the right pins.
So once you changed the locations of the pins U1 did COM1 port then work under windows10?
Changed pin locations, using level shifter MAX3373 and RS485-IC MAX13488 : YES, COM1 is working in Win10
Tested with terminal software : Docklight

Edit : added 2 pictures and description

PCB
Bottom : LP
Middle-Center : Level shifter U2 (MAX3373) with wire correction to connector
Top-Center : RS485 transceiver (MAX13488) with TX/RX signal LEDs on the left
COM1_PCB__004.jpg
COM1_PCB__004.jpg (238.53 KiB) Viewed 6375 times


LP screen with TeamViewer on my PC. Terminal program "Docklight" is sending and recieving characters on COM1.
Screen_COM1_001t.JPG
Screen_COM1_001t.JPG (165.04 KiB) Viewed 6375 times

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