Mercedes SLK World banner

Status
Not open for further replies.
1 - 20 of 25 Posts

·
aka John
Joined
·
13,012 Posts
Discussion Starter #1
So - thought I'd throw this out there since I've got a load of brake light flashers going out.

A forum member who lives in a less restrictive environment than the US/UK asked if I could make a custom, continuous pattern flasher for him, and I said sure, since I'll have some quality time sitting in a hotel over the next month or so.

Got me thinking again about something I'd started and never finished, which was to integrate an accelerometer into the design - something that was stupidly complex and expensive a couple of years ago, but thanks to Steve Jobs and the iPhone, is now available in small, relatively inexpensive silicon with very good resolution.

So basically this would do exactly what the flasher today does - flash a preset pattern of your choosing - probably loads more actually - and additionally flash the third brake light when deceleration is greater than a user selected value.

Two modes would be possible - I could have it flash even if the brake are not applied, or only if the brakes are applied.

I'm hoping to be able to do this in the $100 range as a starting target. I'm about 80% confident I can do that in low run (<50), but will depend on the final design. Prototype code is pretty much done, just waiting on samples of a couple of different accelerometers to arrive.

The install would be more along the lines of SmartTop than what it is today. It would be mounted next to the rear SAM, and would be bolted to the rear electronics bay. Hopefully plug and play, but I suspect would be at least one connection that would be fiddly like the assembly of the SmartTop pins into the CAN connector.

Fully integrated with the SAM, and obviously no errors, along with a bypass mode.


Just thought I'd throw this out and see if there was any interest - R171 only at the moment due to the level of integration required - but wanted to give those who had asked for one of the current models a chance to change their minds....

Also ask for suggestions as to added functionality, comments, general sanity check! :) Basically also the "is it worth the cost?" sorta thing as well..

Time frame is indeterminate - gotta fit this around my real job, but figure a couple of months best case to build a couple of prototypes, test 'em, and the get a low run of PCB's made.

EDITED : No, Louise was NOT happy sitting in the car with me stomping on the brakes taking baseline G readings! As a matter of fact, she may have even corrupted a couple of the data points! :p
 

·
Banned
Joined
·
7,812 Posts
EDITED : No, Louise was NOT happy sitting in the car with me stomping on the brakes taking baseline G readings! As a matter of fact, she may have even corrupted a couple of the data points! :p

:biglaugh:
 

·
Founding Member #2 2008 SLK55 AMG
Joined
·
19,407 Posts
The current version works fine and serves its purpose quite well but will follow this with interest.
 

·
Sadly Woolly has passed away
Joined
·
17,375 Posts
Quick thought - if you're tapping into the rear SAM, and a couple of test cases have stated that it's legal (in the EU at least) to flash the rear brake lights (not just the 3rd 'high level' LED bar ) under emergency braking (I understand the new 'S' class now does this ), why not build that in also? . . . .
 

·
aka John
Joined
·
13,012 Posts
Discussion Starter #5
'tis very possible Woolly, and something I plan on playing with. My biggest concern, actually, is in being able to shake and bake the circuit to the point where *I* trust it if it's hooked to all three lights.

If it dies and takes out the third brake light, meh, not the end of the world. If it dies and takes 'em all out, well...... ;-)

Short answer is probably would require an addition MOSFET (or two?), so negligible cost difference.
 

·
DAS/STAR Premium Member 2005 SLK 55 AMG
Joined
·
4,024 Posts
...count me in... I'll help with testing if necessary too...

S
 

·
Don - Founding Member #4
Joined
·
5,857 Posts
Quick thought - if you're tapping into the rear SAM, and a couple of test cases have stated that it's legal (in the EU at least) to flash the rear brake lights (not just the 3rd 'high level' LED bar ) under emergency braking (I understand the new 'S' class now does this ), why not build that in also? . . . .
:tu:I like this idea in addition to what you propose John.

...count me in... I'll help with testing if necessary too...

S
:tu:DEFINITELY want one also.
 

·
aka John
Joined
·
13,012 Posts
Discussion Starter #8
Sitting at the dentist, thinking about third brake lights. :p

Woolly, what about the fact we have two almost never used, bright bulbs in the tails? Thinking rather that 'risk' a circuit on the primary brakes lights, strobe the rear fogs? Seems like it would be pretty noticeable even with the brakes on?
 

·
Premium Member
Joined
·
277 Posts
Sitting at the dentist, thinking about third brake lights. :p

Woolly, what about the fact we have two almost never used, bright bulbs in the tails? Thinking rather that 'risk' a circuit on the primary brakes lights, strobe the rear fogs? Seems like it would be pretty noticeable even with the brakes on?
I think that's the ticket. No one would want to carry the liability on the primaries.
 

·
Banned
Joined
·
7,812 Posts
Sitting at the dentist, thinking about third brake lights. :p

Woolly, what about the fact we have two almost never used, bright bulbs in the tails? Thinking rather that 'risk' a circuit on the primary brakes lights, strobe the rear fogs? Seems like it would be pretty noticeable even with the brakes on?
Am I right in thinking that not all cars have two rear fogs ??
 

·
Founding Member #2 2008 SLK55 AMG
Joined
·
19,407 Posts
"Strobe the rear fogs" sounds absolutely lovely :tu:
 
  • Like
Reactions: UK-C200

·
Sadly Woolly has passed away
Joined
·
17,375 Posts
Woolly, what about the fact we have two almost never used, bright bulbs in the tails? Thinking rather that 'risk' a circuit on the primary brakes lights, strobe the rear fogs? Seems like it would be pretty noticeable even with the brakes on?
Sounds a good idea, the only problem is that in Europe, it is currently illegal to use your rear fogs in good viz. The chance of being stopped for it however would be minimal, as they would only be activated under 'emergency' braking.

You could always say:-

"No officer, there is nothing wrong with my brake lights - I was taking evasive action from the eejut, who pulled out in front of me, swerved round him, braked hard, and all the while was flashing my rear fogs on and off to warn the retard behind, who was tailgating me." :)
 

·
Registered
Joined
·
44 Posts
John,

What is the cost per unit for the accelerometers that you are using? I work for a company that designs and manufactures them, infact, I'm on the Silicon side of the manufacturing line. Most of our designs are more complex than the std mems used in the iphone but we manufacture and sell them too. We do Gyro's and air bag sensors as well. I might be able to set you up with samples...Usual sale numbers are in the 100's to 1000's so I'm not sure you want to go there yet. PM me when you get a chance.
 

·
aka John
Joined
·
13,012 Posts
Discussion Starter #16 (Edited)
John,

What is the cost per unit for the accelerometers that you are using? I work for a company that designs and manufactures them, infact, I'm on the Silicon side of the manufacturing line. Most of our designs are more complex than the std mems used in the iphone but we manufacture and sell them too. We do Gyro's and air bag sensors as well. I might be able to set you up with samples...Usual sale numbers are in the 100's to 1000's so I'm not sure you want to go there yet. PM me when you get a chance.

Hey Fish - mucho appreciated! I've got some samples coming my way from Analog Devices and FreeScale - with the usual "they well ship when they ship", along with some I was able to pick up in ones / twos from the distribution channel.

I'm thinking that the bog-standard 1.5g chips should be fine for what I want, but I've picked up a couple of the ADXL335 3g versions simply because they were in stock.
 

·
Registered
Joined
·
44 Posts
Well I'm glad your looking at the first company you mentioned. It's the company I work for. If you can give me the contact person I can try to move things along for ya. Won't be back to work until next week though! If these work for you, maybe I can talk with the sales dept and mention what you are doing. They are always looking to broaden the market...and maybe work somthing out in the mean time. I know we won't give them away but it comes close lots of times....Also, let me know which product they are sending samples of...It will be interesting to see how these work out.
 

·
aka John
Joined
·
13,012 Posts
Discussion Starter #18
Well I'm glad your looking at the first company you mentioned. It's the company I work for. If you can give me the contact person I can try to move things along for ya. Won't be back to work until next week though! If these work for you, maybe I can talk with the sales dept and mention what you are doing. They are always looking to broaden the market...and maybe work somthing out in the mean time. I know we won't give them away but it comes close lots of times....Also, let me know which product they are sending samples of...It will be interesting to see how these work out.
Well Fish, you'll be happy to know that the competitors product still haven't arrived, but my ADXL335 did. ;-)

Spent some quality time reading datasheets, and more time putting together some bits and pieces to allow me to calibrate it - and managed to get something up and working to play with just as it started peeing it down rain.

Waited until it stopped for a bit, grabbed my mom - the diligent camerawoman - and took it for a spin. Works a treat, so what I thought I was going to spend a bunch of time dorking around with seems to be working... ;-)

WARNING : Very safe for work - and no, it was not a policeman! ;)

 

·
Registered
Joined
·
44 Posts
John,

Great job. Looks like it's triggering at setpoint as designed. Glad we were the first to ship to you. Sounds like a design in win for us ;-).
I was curious to know if your final design was to have the sensor as a plugin retrofit with the current flasher circuit or would incorporating it require a complete redesign of the module. I'm assuming the latter.
 
1 - 20 of 25 Posts
Status
Not open for further replies.
Top