Sansa e200 - wheel light fade in/out, also display fade in/out

[casainho]

I paid one time for CPU and for memory, I pay constantly for energy on battery!

you know that if the light is on then more batter is being used right? so you end up using more power... especially when you want to get the cpu doing more work which does nothing more than make the display look a bit nicer....

But the light is ON 100% of time now! I would like to turn it OFF at for example 80% of the time, to get a very smooth bright and not a hard like now.

One problem that can arise is electric noise because of PWM. Having a switching frequency instead of light always turned ON, may pass noise from switching current of light, to all the circuit system and degrade the audio signal ??

Anyway, I would like to try have the light at 20% ON when It's now ON time. Maybe It will be good for my auto-formation to do that, because I just have small experiences in microcontollers AVR with GCC-AVR and I should learn how to do good programing in C, with kernels and with ARM devices ;-) :-)

[ROMzombie]

I just disable it though Settings>System>Wheel Light Timeout>Off.  

It's not worth the battery time (or annoyance) to have a blindingly bright LED shining at my face, when it's already got a tactile wheel.

[casainho]

I just disable it though Settings>System>Wheel Light Timeout>Off.  

It's not worth the battery time (or annoyance) to have a blindingly bright LED shining at my face, when it's already got a tactile wheel.

But If you have the option to choose have 10% or others values of the total the wheel light, It will not be blindingly bright LED shining at your face but a smooth beautiful blue light ;-) :-) - that would spend 90% less of battery, in case of 10% of total light.

Until that option for dimming light is true on RB, I have my light turned off.

[cannabisman]

I agree, i would like to see the wheel light be able to dim

[Vchat20]

Agreed with the poster just above me. The feature is desire not just to have it, but anyone who uses the player will tell you that the wheel light is just a -slight- bit too bright for the eyes depending on the surrounding environment. And just like the LCD backlight/brightness, it deserves a way to set a brightness level.

Looking into the source and specifically at the LCD backlight fading code, it already has the basis of doing this kind of thing purely in software and should be relatively easy to adapt I would think to the wheel light (someone correct me on this who has actually written the code. Specifically I'm looking at the fading code which does a nice PWM-ish job with the backlight).

[DB1BMN]

Hello,

first of all I would like to pay tribute to all Rockbox developers as this is my first post in this forum and I (re-)discovered Rockbox a few weeks ago and installed it successfully on a Sansa e250 V1.

I would like also to see a dimming of the brightness of the scroll wheel (fading not necessary).
Why? Well, I dislike the cruel blue backlite of the wheel and wanted to substitute the LEDs by amber color type.
The problem is, that the LEDs are not driven by constant current, but there is only a resistor for each LED. In the V1 hardware theese are the resistors R201 to R204 for LED1 to LED4 respectively which are 47 Ohms each. In addition theese resistors are put on the opposite side of the PCB (in V2 hardware there are on the same side). So a simply exchange of the LEDs from blue to amber will make the new LEDs glow in red destroy them within a short time, because te Voltage along the LED is still fitted to blue. An additional increasing of the resistors is necessary!
Therefore I propose to implement an software PWM algorithm similar like the dimming of display backlite (I did not look at the source code if there it is done by sofware) for driving the wheel LEDs with optional maximum range limitation (e.g. for red, amber/orange, yellow, green, blue white...).
I hope you know what I mean. If you need the currents, voltages, duty cycles etc. let me know, I am more familar to the hot iron than to coding at the moment ;-)

Regards from Germany,
Mark

[AlexP]

Dimming for the existing LEDs is one thing, but it is unlikely that this would make it into the main build purely for one (maybe two) people that change the LEDs, as it provides a nonsensical menu option for everyone.

[casainho]

I made a Rockbox code just to test a PWM on that LED. Since I remember, there are 4 LED and with lower duty cycle on them, we start by seeing 4 spot lights, which is ugly!

Just the actual current to that LED make the light glow on over all wheel, less current (I mean using PWM as I did) do not make all wheel illuminated but instead the 4 points... which I guess no one will like it.

I don't have that code with me, I just deleted it. On that time I wrote a simple task for Rockbox kernel, that just turns on/off the LED, doing a kind of bit bang PWM. I guess is a very simple code for you guys get what you are looking for.

Maybe would be good idea if you take some pictures of it as post them here.

[DB1BMN]

Hello casainho,

 I am very interested on your code/hacking expirience.
Yes this may be true, if you decrease the effective current on the blue LEDs that the brightess will decrease more than linearly (as in fact the current of a diode is depicted by an exponential function), but in my case I need to decrease effective current resp. voltage above the diodes, since the the amber (datasheet: http://www.reichelt.de/?;ACTION=7;LA=6;OPEN=0;INDEX=0;FILENAME=X100%252Fla_t68b-ly_t68b.pdf;SID=27@6@GT4KwQARsAABLKBs9df9f7353d437894c654c0fc8b0570fb) have got a Uf of 2.4 Volts in contrast to blue LEDs with up to 4.5 V.
I will do some exact measurements and pictures this evening and publish them.

Regards, Mark

[casainho]

I am very interested on your code/hacking expirience.

Are you able to make that code?

I can't right now do it, but I can guide on if you need.

I will do some exact measurements and pictures this evening and publish them.

It's always a pleasure to see hardware/firmware hacks ;-)

Do you already know the Lyre project? Where we want to make a good quality Open Hardware audio player and recorder.

[seani]

I said...
the light is either on or off.. there is no hardware dimming possible..
it can be done in software but its not going to be added because im all honesty.. its stupid.

Just not quite as stupid as this sort of response to a polite request.

[DB1BMN]

Hello,

Are you able to make that code?

Yes I hope so. I am familiar to assembler programming for 8051 Microcontroller and C language for PC and microcontroller and bought an Cortex M3 (Arm7) dev-bord a few weeks ago.
If you would give me a guide this would be grate!

The Lyre-Projejt I took a short look at it, I was also concerning about the Beagle Board or Pandora Console as a toy for the bored engineer but finally I ended up with the Sansa e200 and Rockbox for the moment.

Ok, for this time the measurings (of course the LEDs ar switched ON):
* voltage drop above blue LED: 2.98 V
* open circuit voltage after removing LED: 3.3 V
* short circuit current: 66.5 mA

The resistor value is 47 Ohms as I mentioned, this is nearly the same value as you divide 3.3 V / 66.5 mA = 49.6 Ohm, as there is some tolerance and additional resistance from the transistor Q9 ([AE2A] 1R = MMBT5089, npn, V_ce = 25 V, I_c = 100 mA, datasheet: http://www.datasheetcatalog.org/datasheet/fairchild/MMBT5089.pdf) which is common for all cathodes.
From the voltage drop of 0.3 V above the resistor I calculate approx. 7 mA I_F for each LED.
Can this be true that the Diodes can achieve such high brightess at this relatively low current? I did not measure the curren directly yet.

Pictures will follow later on evening.

Regards, Marek

[casainho]

Hello,

Are you able to make that code?

Yes I hope so. I am familiar to assembler programming for 8051 Microcontroller and C language for PC and microcontroller and bought an Cortex M3 (Arm7) dev-bord a few weeks ago.
If you would give me a guide this would be grate!

So you should no need for such a guide ;-) -- maybe you could do what I should on that time -- share the Rockbox firmware file with the wheel light dimming....