LK204 Not returning keypresses when polled

LK/ELK/VK/PK/OK/MX/GLK/EGLK/GVK/GLT Series

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K_Trenholm_GDC
LCD?
Posts: 7
Joined: Thu Jun 12, 2014 1:11 pm

LK204 Not returning keypresses when polled

Post by K_Trenholm_GDC » Thu Jun 12, 2014 1:36 pm

Hi all,

I'm working on getting a LK204-7T-1U running and while most everything is working the one issue I'm having is with polling the keypad.

I am working through an I2C interface and I am sending what I believe to be the correct configuration commands. I am sending the following:
(See screencap attached to post)

<START>
0x50 (address [write])
<ACK>
0xFE (command)
<ACK>
0x4F (auto-transmit off)
<ACK>
<STOP>

<START>
0x50 (address [write])
<ACK>
0xFE (command)
<ACK>
0x60 (auto-repeat off)
<ACK>
<STOP>

I then have a loop that polls the device for new keypresses every half second:
<START>
0x50 (address[write])
<ACK>
0xFE (command)
<ACK>
0x26 (poll)
<ACK>
<STOP>
<START>
0x51 (address[read])
<ACK>
0x00 (data received back from LK202)
<NACK>
<STOP>

Everything seems to be ACKing and NACKing as it should, but the only data I receive back from the LK204 poll keypad command is 0x00 no matter which button is pressed.

Is there a command I am missing? Something else I should be doing?
I have my screencap from the logic analyzer attached to this post.

Thanks in advance for any help
LK204_config_and_poll.png
Config and Poll I2C transations
LK204_config_and_poll.png (33.42 KiB) Viewed 2264 times

Tino
Matrix Orbital
Matrix Orbital
Posts: 158
Joined: Wed May 22, 2013 9:04 am
Location: Matrix Orbital

Re: LK204 Not returning keypresses when polled

Post by Tino » Thu Jun 12, 2014 3:02 pm

Hi,

Have you set the transmission protocol to I2C?
If not send the "Transmission Protocol Select" and set the Protocol to I2C.

This will set the display to transmit data to the host in I2C.

You can also find some general I2C development information that could help here:
http://www.matrixorbital.ca/appnotes/i2c/

Let me know if this helps.
Martino
Martino DeLeon
Matrix Orbital
Technical Support Representative

K_Trenholm_GDC
LCD?
Posts: 7
Joined: Thu Jun 12, 2014 1:11 pm

Re: LK204 Not returning keypresses when polled

Post by K_Trenholm_GDC » Fri Jun 13, 2014 6:41 am

Yes, the jumpers are set to I2C

K_Trenholm_GDC
LCD?
Posts: 7
Joined: Thu Jun 12, 2014 1:11 pm

Re: LK204 Not returning keypresses when polled

Post by K_Trenholm_GDC » Fri Jun 13, 2014 6:54 am

However it was NOT being set in software.
That fixed the issue.
0x50
0xFE
0xA0
0x00

I was under the impression only the jumpers would need to be set.

A note to anyone from Matrix, the documentation for this display could make it a bit clearer that both the jumpers need to be set as well as the software command sent. The section of the manual describing I2C setup makes mention of setting the jumpers to set up I2C but does NOT mention sending the protocol select.

Tino
Matrix Orbital
Matrix Orbital
Posts: 158
Joined: Wed May 22, 2013 9:04 am
Location: Matrix Orbital

Re: LK204 Not returning keypresses when polled

Post by Tino » Fri Jun 13, 2014 8:09 am

Hi,

That's great!

Thank you, I will forward that on to have the command also noted in the I2C set up section of the manual to help avoid the confusion.

Again thank you for posting on our forums.
If you have any other questions or concerns please feel free to ask.
Thank you
Martino
Martino DeLeon
Matrix Orbital
Technical Support Representative

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