OLED and Roboard

[JavaRN]

I recently bought the following OLED display http://robosavvy.com/store/product_info.php/products_id/606?osCsid=c685d104f94ec897cc453551492d5c8c from robosavvy store and I am trying to connect it to roboard using TTL COM3. I have one problem though - I cannot find a place where to connect the reset pin. Does the device work without the reset pin connected?

Thanks, and Merry Christmas to everyone.

[PedroR]

Hi JavaRN

How about connecting the RESET pin to one of the PWM ports and setting HIGH or LOW (with RAW pulses)?? I think this would make for a good solution.

Having said this, from what I've seen, resetting is only interesting when you want to change the baud rate. I don't see any use for it in the docs, so you wouldn't need to implement it.
However because RESET is Active LOW (page 60 of the user's manual) you can't leave it unconnected (this is annoying...). Connecting a Resistor (probably 1K) between the power pin (5V) and the RESET pin, to keep it HIGH (inactive) probably gets it solved.

There are two things to consider though:
>> the OLED uses a UART at 3.3V (and I believe the Roboard is 5V) so you will need a 1K series resistor on the RX line.
On the TX line you should be OK because 3.3V is usually enough to be detected by 5V devices.

>> The OLED has an auto baud rate feature. You need to send "U" after power up to have the OLED lock on to the correct baud rate.
Refer to page 56 of the manual here
http://www.4dsystems.com.au/downloads/m ... Rev1.3.pdf


I must say it is a brilliant idea to use an OLED for output on the roboard.
It is small, cost effective, easy to implement and offers low power usage. In addition it looks great, much better than a serial LCD, to match with the superior quality of the roboard

If you have any additional question please let me know as we may be able to forward it to the manufacturer.

Regards
Pedro.

[PedroR]

I have just come across another very COOL thing for this OLED:

If you upgrade the firmware on the module it enables the capability of playing Videos on the module.

Upgraded firmware files are available here
http://www.4dsystems.com.au/downloads/m ... mC/Serial/

and the explanation on how to play videos is available here
http://www.4dsystems.com.au/downloads/m ... istory.txt

For some reason information about video playback is not available on the Users Manual...
For information about PmmC files (firmware) and how to perform the upgrade refer to page 58 of the uOLED Users Manual here
http://www.4dsystems.com.au/downloads/m ... Rev1.3.pdf

[JavaRN]

Thanks for your reply. I will try to connect the pull-up resistor with the RESET tomorrow. On the manual there is also stated that

the host should make sure it has its Tx line pulled HIGH

otherwise the OLED may unlock onto an unknown baud rate. The manual then suggest that this can be done by

adding a pull up resistor on the host Tx line

pg (66), Is this pull-up resistor needed in Roboard's case?

A point to notice also is that COM3 power is not 5V, In my case I used a 7805 voltage controller.

[PedroR]

Hi JavaRN

I do not know about the need for this on the Roboard. I do not know how stable COM3 is during power up.
I think the issue mentioned on the docs _may_ only happen during power up. If you turn on the OLED at the same time as the roboard it may happen.


There a few considerations though:
1) You can connect the RESET pin to a PWM port and issue a RAW PWM pulse to reset the device once the board is fully initialized and your application starts.
This way you ensure you are in a known state.

2) You can use the resistors they mention. However if you look carefully you will see they reccomend the use of a 1K resitor on the host TX line (oled rx) because the host has the UART at 5V.
In addition, they mention the use of a 10-100K resistor on that same line to fix the issue of the floating TX on the host.
So in the end I don't know the total resistance of the line....

3) I had mentioned using a 1K resistor on the RESET pin in my previous post but this may be too low.
I would start by using a 10K resistor on the RESET pin.
This resistor needs to be in place whether you connect it to the 5V pin directly or to the PWM port because I think the PWM signal is also 5V

Bear in mind that I am not an expert in electronics. I have much more experience with software than with hardware so my suggestions above (especially about resistor values) are really... suggestions
To be on the safe side I would start with high value resistors (10K) and then lower the value if they don't seem to work.

Regards
Pedro

[JavaRN]

I tried with 10K resistor for the RESET, still nothing. Unfortunately I cannot work with the PWM ports as I am using java as a programming language and I cannot work through the WINIO.DLL. I will now try to use another resistor (this time a pullup one) with the TX and see what happens. I'll post later on today.

[PedroR]

Hi JavaRN

How about writing a small file in some other language (C) that issues the pwm pulse to reset?
I believe that from JAVA you can start other processes, right?

It is not a pretty solution but it may work.

Also, when you say you get "nothing" what do you mean?
It will not power up?

Have you tried using it on your PC with a USB2Serial converter just to make sure the module is working fine?

Regards
Pedro.

[JavaRN]

How about writing a small file in some other language (C) that issues the pwm pulse to reset?
I believe that from JAVA you can start other processes, right?

Yes I was thinking about that possibility, but first I have to make it work

Regarding to "nothing", what I am getting is the splash screen for the OLED, it is as if the communication is not established.

[PedroR]

I believe you have received a free USB to TTL UART Serial adpater with the module right?

I would recommend using it to connect the OLED to your PC and use a terminal program to communicate with the module and troubleshoot it.
I have recently started using TeraTerm http://en.sourceforge.jp/projects/ttssh2/releases/ and it seems quite good.

As a final note I was wondering if the splash screen you are seeing continuously could be caused by the module being continuously issuing a RESET on itself...

Then again, I think that doing some testing with the USb to Serial adpater and the terminal program might be a good option.

Regards
Pedro

[JavaRN]

It worked, with just RX TX 5V and GND, no need for RESET and no need for the pull-up resistor, the only thing was that in the system it is not COM3 but COM2 !!!!!!

[PedroR]

oh well, I guess the "keep it simple" worked

With regards to the COMM number, please let us know how it goes!
As long as it works...

[JavaRN]

I've sent you a PM regarding the OLED display.