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Hi all,

I have the same Raystar like Jbdriver.
On a LPC17 Core with 5V and 3.3V it is working like a charm.
But on the STM32F4 (MB997D) it is not working, same issues like jarvis:


When I have the power at 3.3v, both displays start up fine but as soon as it loads the Seqv4 app it immediately reboots. If I start up with only 1 LCD connected at a time, the boot sequence works just fine.
When I have the power at 5v, the Seqv4 app loads fine but only the left display functions correctly - the right one shows some random characters.

What I have tested yet:
* External power supply with 5V (Pin J2) and 3.3V (J15_S middle Pin) is not working.
* Also with the 3.3V regulator from LPC17 Core it not working.
  - STM32F4:J2 -> LPC17:J2
  - LPC17:J15_S Pin 3v3 -> STM32F4:J15_S middle Pin
  - STM32F4 USB and LPC17 power supply

The left display is also not working 100% correctly. Some characters are wrong
In my opinion it is a timing problem with the enable pins.

Where can I set the "LCD type to 0x02"? In MIOS terminal this option is missing for STM32F4.

Best Regards

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Thanks for your help.
With the installed sequencer this option is still not available.
Only if the bootloader alone is installed.

Following steps are working for me:
1. Upload only bootloader
2. Connect the LCDs
3. Start MIOS Studio
4. Enter following into MIOS Terminal

set lcd_type 0x02

5. Upload midibox_seq_v4_092
=> Working :grin:

Only issue on 5V the LCD starts stinking (not like on LPC17 Core), so I changed to 3V and everything is fine now.
Except the 3V3 Regulator getting really hot.

Best Regards

Edited by Jack
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  • 2 weeks later...

Hey people,

I have a problem with my OLEDs. I can get the first 8 OLEDs working without any problems. But the 9th OLED is mirrored with the 8th. 

I use the STM32F4 core and I used the 2nd E-line for the 9th display that is available at PC9 of the STM32F4. Do I have to enable this line in the firmware? Can't find anything about it.


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13 minutes ago, latigid on said:

Did you define the max number of LCDs? I have some PCBs that provide more CS lines on simple headers if you need.

You mean in the bootloader? Yes of course! 
I only need one more CS. Can you tell me where to get it from? This schematic:


says, at J28 are four CS available. But the STM-core has no J28. 


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  • 3 months later...
  • 5 months later...

Hey, jumping in this topic with a slight necro-bump. I'm currently assembling the BOM for a new Seq v4 build and am wondering if this is the correct part for a yellow OLED that will be suitable: https://www.mouser.ca/ProductDetail/Vishay-Dale/O040N002ALPP5N0000?qs=sGAEpiMZZMshRHSPqbouvIwO3l5fqdBAixDXe9yjARerJD7W12iKVA%3d%3d

Also, what other changes to the BOM for the rest of the kit are necessary to accommodate this - do I need to upgrade any of the power supplies or add another one, or regulation somewhere? I've read this thread twice and I'm still confused about which exact components ended up being problematic for folks and what they ended up doing to replace them. It's not easy to get parts around here and shipping to Canada from the states is always expensive so I'd really rather get my BOM right the first time if I can.

Thanks for any help or advice you're willing to share! 

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