PreenFM > preenfm2 and preenfm3
Stm32F4Discovery port
noyzelab:
just posting a pic of non-functioning attempt at getting this firmware going on an old board. I ended up abandoning its previous project and removing other parts.. so thought might as well try and get it used for something.
I was wondering how easy it might be to get a minimal build to see if I can download the firmware correctly. Is it possible to just get a bare board+the required usb stick and test to see if appears over USB?
I didn't get anything on the LCD, but I was hoping might see something over the USB in a MIDI app but nothing..
I dont have much/any more time to look at it for now, but thought might try and revive this thread and see if anyone else has been trying this board?
domdel:
Hi
trying to build my own one (see attached pictures) it seems something is not going right: display does not light at all.
I have triple checked all connections to be OK.
As I have an OLED display, it needs full 5V and therefore V+ does not go through the diode next to USB connector. It does not need either V+ & GND on pins 15 & 16 neither the pin 3 needs the contrast signal.
I have flashed the board from Linux, using the st-tools from debian.
When connecting the Micro USB,
* green led lights
* red led next to micros USB lights
* the multi-color led next to XTAL blinks red.
Therefore I have a few questions:
* what is the boot delay ?
* Is it normal to have the red blinking ?
* Are there jumpers on board to change to boot ?
* any clue about display ?
* has anyone experienced a failed display e.g. while soldering or ... mixing up connections before fixing them ?
* any other element that prevents from booting ?
* Has anyone got issues with flashing through Linux ?
I am looking a ST documentation to see if it helps but I would be happy to hear from any knowledgeable person :-)
EDIT thus a question:
* Can someone confirm the preenFM2 firmware talks to a display in 8080 mode ?
It appears mine is using 6800 mode.
* Has anyone already written code for a 6800 mode display ?
Regards
Dominique
solipsvs:
this is the smd board? did you get it on some electro forum?
domdel:
Hi
that is a STM32-f4 discovery board, following Norbim work, using his git repository https://github.com/norbim1/preenFM2. It is a fork of the standard PreenFM2 firmware to adjust to the differences one finds on that board like onboard DSP, no need for duplicating ports ...
My issue seems to have purchased a 6800 type of display when, if I understand the code, the preenFM2 code for the LCD display (apparently not modified by Norbim) seems to address a 8080 type of communication.
At the moment, I am trying to learn about differences and how that would alter the code.
To start with, the Enable pin of the display works opposite : values seem to be taken into account on the descending front rather than High value.
Whilst I am an "old" programmer, I am not familiar with "bare metal" and I look for some indications how I could tweak the code in LiquidCrystal.cpp and make it talk the 6800 dialect.
EDIT
mm well, I might have been too fast thinking I had found the cause. It seems some real PreenFM2 are using the same display (Vishjay 020N004A-GP-GPP05...) Hence my interpretation is probably wrong...
Regards
Dominique
norbim1:
Hi Dominique,
My version was made with an OLED display too, and it definitely needs the diode between V+ and +5V. The Disco board pins couldn't give enough high level for the OLED control, so I lowered the V+ supply a bit with the diode. Another solution would be some level shifters between the Disco pins and the OLED control pins.
I checked Your OLED's datasheet and the minimum input high level is the same as my screen: 0.8*VDD. This means that You need at least 4V, but the disco outputs only provide somewhere around 3V. The diode in the power line causes minimal brightness decrease while the input high level comes quite close to the needed value.
Norbim
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