Problem getting S64128K to startup
Hi,
I am an engineer for lighting control company. I recently used the S32128A for a architectural lighting controller and a theatrical light board.
I chose to use the S64128K for an addtional arch. control product due to similarity in the driver and appearance of the display while adding more screen space.
I have the device configured for 3X step up (We also used this on the S32128A). The initialization code appears to be the same for both displays.
We have not been able to get the display to turn on. Vout remains at approx 3V.
I will note that in debugging it was found that pins 19 & 20 were swapped in the PCB decal. This would have put a cap across CAP1N and CAP2P also cap across CAP2N and CAP1P. I do not know if this would have consequence.
I am attaching schematic and init code snippet for review in case I missed something in migrating a new design based on S32128A.
Thanks
Attachment: lcdintfc.pdf (47.0KB)
Attachment: st7565.pdf (15.0KB)
Hi Mark,
Please see response below from the factory:
Regarding the connection for Vout, CAP3P..., V4... on customer schematic, seems they are quite different from our one, please forward our 64128K tester schematic to him, so that they can modify their circuit as per it.
By the way, the capacitors used should be 1uF ceramic capacitor.
You can find our schematic for the S64128K by clicking the link.
http://displaytech-us.com/pdf/Schematic/S64128k_l_m-testerschematic-080311.pdf
Thanks.
I will give this a shot. My design is based on information from the ST7565 datasheet for 3X. Will look at the cap values and type. I recall from datasheet cap range to 2.2uF.
I'll post results.
Hi Mark,
Please see the attachment which shows the differences between the various versions of the ST7565.
Thanks,
Terry
Attachment: ST7565 S_V_P_R version difference.pdf (16.0KB)
Hi Terry,
I was able to get the display running. The software engineer working on the related project had taken out a line of code that sent the "display on" command. There was a PCB decal issue for the display that I resolved prior to my original post (two pins swapped). The SE in troubleshooting (with pin swap problem) removed the line of code. In the end the only thing that needed to be changed in the init we used on the S32128A was to increase the contrast setting. There was also a command to set booster ratio, but I believe this register is zero by default.
On an aside, the original 3X booster design works fine. The schematic provided by the factory suggested 4X.
I also contacted Sitronix on the capacitors. Either type were fine. I am going to switch over just so all caps are the same.
Otherwise I really like these displays. They are small and fast.
Thanks for your support.
Hi Mark,
Thank you for the feedback. Glad to hear the displays are working well for you! Let us know if you need anything else.
Regards,
Terry
?Hi Mark,Please see response below from the factory:Regarding the connection for Vout, CAP3P..., V4... on customer schematic, seems they are quite different from our one, please forward our 64128K tester schematic to him, so that they can modify their circuit as per it.By the way, the capacitors used should be 1uF ceramic capacitor. You can find our schematic for the S64128K by clicking the link.[url]
-terrydtech
I am working with the same display and I am experiencing several issues with the power system of the LCD (it is difficult to undestand if the internal power systems works or not due to the fact that the power at condensors terminals is every time equal to 3 volts). I followed the sample reported at link and I have the following questions: 1) do you have any specification on the type of condensors to be installed (i.e.: ceramics, electrolyte, polyester,...)? Should the capacitors be ceramic type SMT or also electrolyte work well? 2) when the display is feed by way of 9 volts as per your schematic external supply, it shows a cloudy aspect (points not well lightned and not related to the instructions sent to the display), do you think the problem connected with the internal power system? 3) There is a way to verify if the internal power system work well or not?
I have experienced similar issues during development using this display. It is not a display issue. Based on your post you see only 3V on Vout, though if you force it to 9V using external supply you see some activity but it is still not correct. This is more indicative of a hardware or programming problem.
1. The caps are a non-issue, you can use ceramics, tantulum, or electrolytic. This is based on info from engineering at Displaytech. I finalized my design using all 1uF ceramics, makes sense, cheaper and they work fine.
2. Make sure that your hardware is correct. The step-up circuit, all control signals and data go to the correct pins.
3. Make sure the timing is correct. The part is very fast, I would think the biggest concern may be the write or read pulse width depending on the processor and its speed. min. width 80ns.
4. Check your initialization code and make sure you have contrast set high enough AND that the DIsplay ON command is sent. I have attached a snippet from my code to init the device. I have seen other variations including multiple steps to enabling each part of the internal step circuitry. Ultimately it wasn't needed.
Hope this helps
Attachment: S64128Kinit.c (3.0KB)
Hi markktoo.
Thank you for your message.
The configuration I am currently use foresees a PIC 16f887 working at 4 MHz.
By means of read instructions, I checked that commands I send to the display were correct (for example: ''display on'' could be verified on bit 5 or ''reverse mode'' on bit 6, using read status instruction).
In addition to that I did a check of writing to dispay, with adressing of column and then reading to display memory and also this test was fine.
On the basis of that, I was thought that the communication and connections were correct . I did the tests also with a new display and also in this case the result was the same...
A couple of questions:
1) when you say Vout, you mean the power at display pin 26 (i.e. V zero) or you mean V at display pin 16?
2) When I write data or commands to the display, I am proceeding in that way:
2.1) put the 8 bits to be transferred to the display on PIC PORT
2.2) put E high
2.3) no operation
2.4) put E low
I have understood that the timing of 2.2 to 2.4 shall be at least 80nanoseconds... but do you know if a too long time (for example 1 second) may generate issues?
Thank you.
Based on your post you are writing/reading correctly.
1. Vout is at pin 16 on the display.
2. Your description for writing appears based on 6800 interface selection. However, you do not mention anything about R/W. E is a clock for 6800. Although you indicate writing/reading correctly. Specification of the ST7565, like many just indicates a minimum pulse width. A longer time shouldn't be a problem.
You should still verify all hardware connections using an ohm meter.
Yes: I would work with a 6800 interface and use R/W bit for Reading instruction (bit high) or Writing Instruction (bit Low). The procedure that I follow is therefore this one:
1) fix R/W to 0 for command or 1 for display data
2) put the 8 bits to be transferred to the display on PIC PORT
3) put E bit high
4) no operation
5) put E bit low
Just another question: on the basis of electrical scheme available on this web site, I have understood that the 9 volts shall be connected at pin 26 of display (V zero) and I did the connection in this way having some sign of live from the display.
When the display will work correctly, do you know in which way should change the Vout on pin 16?
I would follow your advice and check the electrical connections.
Bye.
Hi,
I am working for a Investigation Center at Public University of Navarre.
I am using the LCD module 64128M intead of the LCD module 64128K and I am having some problems with the LCD initialization.. I have achieve to put all the points on with the "Display all points on instruction" but there are some dots that still stay when turning to the "Display all points off" instruction, what can be the problem??
Thanks!
