Stromputer is alive - Page 15 - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums

BigMan73 · #**141** 01-16-2013, 11:35 AM

Quote:

Originally Posted by the schwartz

yeah i left the ones blank that i didn't know about

sorry - i've done 2 or 3 projects before but i'm still really new to this as well.

I'd guess that the LED resistors are for lessening the brightness of the LED lights. I'm not certain and I think that could be controlled as well/instead through the Arduino, but maybe they're so stupid bright that the resistors are useful for setting a max brightness.
edit: why you need resistors with LEDs

LED resistors are current limiters - Most LEDs cannot tolerate more than 20-25mA. The resistors limit the current to these values.

The brightness of LEDs in Stromputer is controlled by using PWM - Pulse Wave Modulation. That is why the particular digital ports were used for LEDs. Only these ports support PWM.

the schwartz · #**142** 01-16-2013, 11:37 AM

Quote:

Originally Posted by BigMan73

LED resistors are current limiters - Most LEDs cannot tolerate more than 20-25mA. The resistors limit the current to these values.

The brightness of LEDs in Stromputer is controlled by using PWM - Pulse Wave Modulation. That is why the particular digital ports were used for LEDs. Only these ports support PWM.

thanks. this makes sense to me.

does the brightness of the LEDs change based on what the photocell's picking up (brighter LEDs if it's daylight shining on the photocell, dimmer LED if it's nighttime)? If not, what's the photocell for?

BigMan73 · #**143** 01-16-2013, 11:43 AM

Quote:

Originally Posted by the schwartz

thanks. this makes sense to me.

does the brightness of the LEDs change based on what the photocell's picking up (brighter LEDs if it's daylight shining on the photocell, dimmer LED if it's nighttime)? If not, what's the photocell for?

Yes, the photocell is used for doing exactly that.

But for NHD LCD modules (note: do not confuse LCD with LED!), it also controls the brightness of the LCD automatically.
YwRobot LCD modules have no way to control brightness programatically so the LCD brightness is constant.

BigMan73 · #**144** 01-16-2013, 12:05 PM

Quote:

Originally Posted by the schwartz

question: should the Posi-Locks still be on there? I thought they were POSi-locks per one of your posts, yes?

Yes, but they are optional.
You need to hookup power from the 12V battery (Black for GND, Red for 12V) and to the GPS line (Green that connects with Blue Posi-Tap, or directly to the Pink GPS line of the V-Storm, I recommend a Posi-Tap, perhaps it should be added to the BOM)

You solder the lines directly, or use a fuse box - it is up to you.

the schwartz · #**145** 01-16-2013, 12:43 PM

Quote:

Originally Posted by BigMan73

Yes, but they are optional.
You need to hookup power from the 12V battery (Black for GND, Red for 12V) and to the GPS line (Green that connects with Blue Posi-Tap, or directly to the Pink GPS line of the V-Storm, I recommend a Posi-Tap, perhaps it should be added to the BOM)

You solder the lines directly, or use a fuse box - it is up to you.

Blue Posi-Tap is 16-18 Gauge. Is that the size of the GPS wire?
also seems that the Posi-Taps only come in packages of 6 for $9 (through the manufacturer at least)

BigMan73 · #**146** 01-16-2013, 01:07 PM

Quote:

Originally Posted by the schwartz

Blue Posi-Tap is 16-18 Gauge. Is that the size of the GPS wire?
also seems that the Posi-Taps only come in packages of 6 for $9 (through the manufacturer at least)

I did not measure the GPS wire size, but the Blue Posi-Tap works just fine with it.
Yes, it does come in a package. Maybe you can find something on ebay that comes as a single, or maybe there is something similar in AutoDepot/RadioShack - I did not check there.

BigMan73 · #**147** 01-16-2013, 01:27 PM

I committed an updated BOM to SVN, based on 'the schwartz' updates.

BigMan73 · #**148** 01-17-2013, 11:48 PM

I added some documentation of how to compile the source code:
StromputerV2Instructions - stromputer - Display enhancement for Suzuki V-Strom motorcycles (and others) based on Arduino - Google Project Hosting

Also thanks to Chris, I found that there is an issue with the analog to digital calculations which I did not noticed on V1, but which is an issue on V2 (in particular the Nano V3 board) when connected to USB power. When using the LM2940 5V voltage regulator, i.e. on the motorcycle, this is a non-issue.
It has to do with the internal voltage (VCC) on the board. IT seems on Nano V3 the VCC is much less than 5V, causing voltage calculations to skew considerably. Once again, it should work flawlessly on the bike since VCC will be a nice stable 5V, thanks to LM2940.
I will fix and verify that during this weekend. Not a show stopper and causes no risk, just something to be aware of.

TheWall · #**149** 01-18-2013, 12:19 AM

Quote:

Originally Posted by BigMan73

...Also thanks to Chris, I found that there is an issue with the analog to digital calculations which I did not noticed on V1, but which is an issue on V2 (in particular the Nano V3 board) when connected to USB power. When using the LM2940 5V voltage regulator, i.e. on the motorcycle, this is a non-issue.

It has to do with the internal voltage (VCC) on the board. IT seems on Nano V3 the VCC is much less than 5V, causing voltage calculations to skew considerably...

Doesn't the Arduino have an internal voltage regulator? Shouldn't it be providing a stable Vcc regardless of the power source?

Is the Arduino expecting USB voltage to already be regulated, and therefore Vin from the power jack goes through the regulator, but not the Vin from the USB port? That's kinda a poor design for the reasons you mention above if that's the case, but I'm only an interested neophyte in the EE world, so maybe there's something I'm missing that explains why it's working that way.

BigMan73 · #**150** 01-18-2013, 07:40 AM

Quote:

Originally Posted by TheWall

Doesn't the Arduino have an internal voltage regulator? Shouldn't it be providing a stable Vcc regardless of the power source?

Is the Arduino expecting USB voltage to already be regulated, and therefore Vin from the power jack goes through the regulator, but not the Vin from the USB port? That's kinda a poor design for the reasons you mention above if that's the case, but I'm only an interested neophyte in the EE world, so maybe there's something I'm missing that explains why it's working that way.

AFAIK Arduino Nano do not regulate voltage when connected to USB. There is a bypass.
I don't think it is a poor design, but rather my assumptions about the ADC reference being 5V were just incorrect. Once VCC is taken into account (very easy) the ADC calculations are very accurate.

The other thing you need to know is that voltage regulators have a drop out voltage parameter - i.e. They need some buffer above their regulated voltage. LM2940 for example has a low dropout of 0.5V. So to regulate to 5V one needs to feed at least 5.5V
Other, lesser quality regulators, require even a higher dropout, so you would need 6V or even 7V to regulate to 5V.
And indeed if you look at the Nano spec: Arduino - ArduinoBoardNano
"Input Voltage (recommended) 7-12 V"

which means the internal regulator (which is not used in Stromputer) has a dropout of 2V. In Stromputer the LM2940 stable 5V bypasses the internal regulator by going into Vin pin directly.

EDIT: For those interested to learn more about this, http://hacking.majenko.co.uk/node/57

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