Recent Posts

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21
PreenFM2 / Re: Yellow OLED : high frequency solution
« Last post by Godric on November 27, 2017, 07:08:11 PM »
I'm assuming the power connector ground would be a good place?
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PreenFM2 / Re: Yellow OLED : high frequency solution
« Last post by Godric on November 27, 2017, 01:06:12 PM »
I made a shield as described, which seems to be working (at least I'm not aware of any noise). I was then sent a shield by Ardi at Vandaal, as it (and a volume knob) had been missing from the kit when it was posted out.

I notice Ardi's shield has a wire soldered to it and I assume that the other end needs to go to Ground or 0V. Any suggestions about the best place to solder this shield to?

Godric
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PreenFM2 / Re: Vishay OLED brightness
« Last post by alien_brain on November 27, 2017, 05:14:49 AM »
thanks man, not trying to be a pain.  my white euro rack adaption just wouldnt be complete without a white oled.  pfm2 is a very nice looking synth if you ask me.  white display would make it more so
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PreenFM2 / Re: Vishay OLED brightness
« Last post by Xavier on November 26, 2017, 10:15:43 PM »
my tech has them in his tx802 and tx81z at full brightness and was looking to try to find where the limiting resistor that is on the rev c pfm2 PCB...   there isnt one?

What limiting resistor are you talking about ? I don't get it.

A small update : I put today a 2x40 white oled in my ambika and it works great.

I have no idea what the problem is with th 4x20 white OLD in the preenfm2. I'll update this thread if i find something.
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PreenFM2 / Re: Vishay OLED brightness
« Last post by alien_brain on November 26, 2017, 07:47:40 PM »
my tech has them in his tx802 and tx81z at full brightness and was looking to try to find where the limiting resistor that is on the rev c pfm2 PCB...   there isnt one?
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PreenFM2 / Re: preenfm2 editor 2.08.4 (November 25th 2017)
« Last post by Xavier on November 25, 2017, 05:08:54 PM »
Audio Unit for mac is available with 2.08.4 as well as a couple of new stuffs:
https://github.com/Ixox/preenfm2Controller/releases
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PreenFM2 / Re: Vishay OLED brightness
« Last post by Xavier on November 25, 2017, 12:31:29 PM »
so is there a resistor that can be changed so this display is as bright as other colors?

No, white oleds are much less bright.
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PreenFM2 / Re: Vishay OLED brightness
« Last post by alien_brain on November 25, 2017, 11:02:56 AM »
so is there a resistor that can be changed so this display is as bright as other colors?
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PreenFM2 / Re: PreenFM2 SMD version - F1 firmware
« Last post by zelea2 on November 25, 2017, 02:35:20 AM »
I have finished a rough version of the STM32F103 firmware
If anyone wants to have a look it's here http://uglyduck.ath.cx/PreenFM2_SMD/SurfaceControl_F103.tar.gz

The processor sleeps most of the time, it's only awaken by the systick interrupt every milisecond or by a surface event or a SPI command. I have 5 encoders + 5 encoder switches + 7 switches so that's 17 and the processor only has 16 EXTI lines. So switch 6 has to be separately scanned every milisecond.

At the start a LED is flashed 6 times so you can see the processor is alive. A second LED near encoder5 shows the function of this encoder - if it's lit then the encoder acts as a global volume knob and doesn't generate a surface event. The volume is adjusted by the F1 alone.

Every time a surface event occurs the F1 raises an interrupt line. The main processor can read the entire surface status with two 16bit SPI transfers whenever it has time. Each encoder can memorize up to 7 steps. A second SPI interface controls the digital potentiometers. Both SPIs are at 2Mbit/s which is maximum for its internal 8MHz clock. All SPI transfers are handled by the DMA.

One command also allows the F4 just to read the switches status in real time (maybe useful to detect long-presses). I have so far 7 commands from F4 that I handle. Is there anything missing?

The volume scale is logarithmic. The F1 initializes the number of volume steps with a default value. The F4 can also change the number of steps. Each of the 4 audio channels have a maximum volume fixed at 255 at the start. The F4 can also change the top value for each channel at any time.  The global volume acts as a fraction of this top volume value.

I've split the flash memory in half and I'm using the last part to store some non-volatile local variables. So far I only have the current volume position and the volume number of steps.

For now I'm relying on the external caps for the debouncing but what I plan to do is to use all the available 4 timers in a round robin scheme  to start a one-shot count when a switch/encoder is pressed and ignore any following presses until the timers elapse. With 4 timers I can keep track of 4 simultaneously pressed switches/encoders.

Any suggestions are welcomed.
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PreenFM2 / Re: new build LCD lit but blank
« Last post by ghostofjohntoad on November 25, 2017, 01:18:20 AM »
OK I solved it.  Didn't realize I needed a connection in the OLED resistor spot.  Put a wire there it it works great.  Awesome sounding!
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