Search found 18 matches

by SecretSquirrel
Fri Jul 03, 2015 12:05 pm
Forum: AVR Microcontrollers
Topic: Why is Attiny85 so popular?
Replies: 22
Views: 5537

Re: Why is Attiny85 so popular?

I'm confused about why the Attiny85 is more popular (on hobby electronics sites) than the picoPower microcontrollers like Attiny43U. Why doesn't everyone want the lowest current consumption, as well as an Attiny with a built in booster to 3V? I'm not sure if there's something I'm missing. I have be...
by SecretSquirrel
Wed Apr 06, 2011 8:09 pm
Forum: Wireless/RF
Topic: RN-42 in HCI Mode?
Replies: 4
Views: 1149

Re: RN-42 in HCI Mode?

Does anyone have any experience using the RN-42 in HCI mode? I need about 400k baud which is too fast for the SPP mode. The datasheet says that "the RN42 module must be loaded with special firmware to run in HCI mode" yet the datasheet doesn't mention how to do this at all. Does anyone know how to ...
by SecretSquirrel
Thu Mar 24, 2011 5:00 pm
Forum: SparkFun Product Questions
Topic: OBD-II-UART and Bluetooth Mate Silver
Replies: 3
Views: 1148

Re: OBD-II-UART and Bluetooth Mate Silver

In my day job, I work in an IT operations organization and do a lot of customer support. First rule? Any information the customer gives you is suspect at best. In politically correct situations, this is known as "trust but verify". I failed to follow that rule as I was the one providing the informat...
by SecretSquirrel
Mon Mar 21, 2011 11:13 am
Forum: SparkFun Product Questions
Topic: OBD-II-UART and Bluetooth Mate Silver
Replies: 3
Views: 1148

Re: OBD-II-UART and Bluetooth Mate Silver

SecretSquirrel, I really wish I could help with this, but I haven't anything to offer. I just thought I should point out that you've done a beautiful job of asking your question. Eric Thanks I guess. Looking back on it, I might could have organized my thoughts a bit more. I was rather miffed at hav...
by SecretSquirrel
Wed Mar 16, 2011 7:41 pm
Forum: SparkFun Product Questions
Topic: OBD-II-UART and Bluetooth Mate Silver
Replies: 3
Views: 1148

OBD-II-UART and Bluetooth Mate Silver

So first, the questions about the OBD-II-UART. Looking at the Eagle files for the board, it appears that the NC pins are not connected. However, on my board, with power applied, I get about 4.7V on the NC pins. I am asking as I managed to fry my board somehow. This leads into the Bluetooth Mate ques...
by SecretSquirrel
Wed Nov 17, 2010 7:48 pm
Forum: SparkFun Product Questions
Topic: The Open Lidar Project - Hack the Neato XV-11 Lidar for $$
Replies: 9
Views: 2175

Re: The Open Lidar Project - Hack the Neato XV-11 Lidar for $$

Ah, so they used my second guess. Triangulation in 2d space. That explains the significant angular offset of the laser from the camera. At maximum range the laser dot needs to be on the far left of the frame for best resolution. Reading the paper, I would think that spending a little extra on the la...
by SecretSquirrel
Wed Nov 17, 2010 4:01 pm
Forum: SparkFun Product Questions
Topic: The Open Lidar Project - Hack the Neato XV-11 Lidar for $$
Replies: 9
Views: 2175

Re: The Open Lidar Project - Hack the Neato XV-11 Lidar for $$

You could also, with a tight beam divergence, measure the distance off center of the beam dot. The farther off center the closer it is. You only have to process one line of video, but the trade off is that distance resolution will be determined by the resolution of the camera and by the distance of ...
by SecretSquirrel
Wed Nov 17, 2010 3:38 pm
Forum: SparkFun Product Questions
Topic: The Open Lidar Project - Hack the Neato XV-11 Lidar for $$
Replies: 9
Views: 2175

Re: The Open Lidar Project - Hack the Neato XV-11 Lidar for $$

Hmm. So we have a single laser module and a single "camera". I'll assume its a standard CMOS sensor, probably QIF format, maybe VGA. How would I do it? Use a IR laser and remove the IR filter on the camera. Now, the trick? Set the laser optics to have a fairly high beam divergence. The higher the di...
by SecretSquirrel
Wed Nov 10, 2010 12:42 pm
Forum: SparkFun Product Questions
Topic: 2-bit ALU with NPN transistors, resistors and LEDs?
Replies: 22
Views: 5784

Re: 2-bit ALU with NPN transistors, resistors and LEDs?

Sounds really cool, SS! Nothing like a project to lighten up your working day! (sorry horrible pun...) However I do see that I might run into a problem powering all of the LEDs. If all of the 52 LEDs (2.2-2.4V / 20mA) I am planning on using will be turned on at the same time they will use 52 x 20 m...
by SecretSquirrel
Thu Oct 28, 2010 10:58 am
Forum: SparkFun Product Questions
Topic: 2-bit ALU with NPN transistors, resistors and LEDs?
Replies: 22
Views: 5784

Re: 2-bit ALU with NPN transistors, resistors and LEDs?

I suspected there was some artistic desire in the project. It has be considering laying out a similar board and driving it with a random number generator to get a good "blinky light" display. :) I might go surface mount to keep the board size down so I can hang it on the wall in my office.

--SS
by SecretSquirrel
Fri Oct 22, 2010 8:52 am
Forum: SparkFun Product Questions
Topic: 2-bit ALU with NPN transistors, resistors and LEDs?
Replies: 22
Views: 5784

Re: 2-bit ALU with NPN transistors, resistors and LEDs?

You can potentially reduce the component count by removing the four redundant gates in the logic section of the ALU. If you notice, the adder performs an AND of the two bits so there is no reason to include a separate stand alone AND gate. Simply tap the AND signal from the appropriate point in the ...
by SecretSquirrel
Wed Apr 08, 2009 12:56 pm
Forum: GPS
Topic: EM-406A and time synchronization
Replies: 3
Views: 2410

The PIC has a three instruction cycle latency for interrupt execution. Depending on the synchronization of the processor clock and the interrupt, the latency will be either three or four instructions depending on when in the four clock instruction cycle the interrupt occurs. ISR execution time will ...
by SecretSquirrel
Thu Nov 13, 2008 7:16 am
Forum: Code
Topic: Atmega32 as timing system?
Replies: 18
Views: 8117

What I think we're going to go with is pre-loading the Timer so that it runs in 100mS overflows. Every time if overflows, the ISR increases a variable by 1. In the main code it's only polling each of the unmasked lanes continuously, and in a rotating pattern. No other code involved in this loop. Bo...
by SecretSquirrel
Mon Nov 10, 2008 8:21 pm
Forum: Code
Topic: Atmega32 as timing system?
Replies: 18
Views: 8117

I don't know how anyone could have arrived at a figure of 0.31 seconds of inaccuracy. At an 8MHz clock, your interrupt service routine(ISR) would have to take over 2.4 *million* cycles to complete. I don't know about you, but I have a hard time wasting that many cycles on purpose much less doing it...
by SecretSquirrel
Sun Nov 09, 2008 9:49 pm
Forum: Code
Topic: Atmega32 as timing system?
Replies: 18
Views: 8117

Re: this is being made way too complicated...

If it were me, I would use the 16 bit timer (assuming the mega32 has one and I'm pretty sure it does) and then use one of the other general purpose registers to count the overflow. You still get a 24 bit count, but you then don't have to deal with counting code cycles and worrying that one code pat...