Product Design (Parking Assistant Alarm) - Page 1
Forum section: electronics / projects

author: Scutarius
author_rank: Regular Contributor
timestamp: April 19, 2010, 10:46:51 pm
content: Hi !!!Well I got a job, my first job, and I am very enthusiastic about it, I suppose to be a hardware designer (kinda, I Have a bachelor in electronics, m.sc. in process) I my first project is a simple parking assistant alarm, this is useless product maybe, somebody just ask for this product to the company, but for me it is a good opportunity.This is how it works, it will be a "ball" enclosure with a simple sensor and LEDs, that is all.If the car hits the ball it flashes, (useless I think, but never mind), so I was ask to use a PIC a SQ-SEN-200 sensor and 2 LEDshttp://signalquest.com/sq-sen-200.htmthe webPIC12F675, I used this schhttp://itp.nyu.edu/physcomp/sensors/Reports/SQ-SEN-200I am coding in MikroC pro 2009, I am going to use int's, but I it is harder for me the code.I attach the screenshots, sch and pcb, please if you think that I am doing something wrong or if I can do it better post it!I just wanna learnI am using the battery clips from newark (56P4899) to reduce cost1.-Bypass capacitor close to Vdd

author: Scutarius
author_rank: Regular Contributor
timestamp: April 19, 2010, 10:52:05 pm
content: I cant attach fileshttp://rapidshare.com/files/377819537/xdyzio.rar.htmlsamehttp://rapidshare.com/files/377819867/xdyzio.rar.html

author: TheDirty
author_rank: Frequent Contributor
timestamp: April 20, 2010, 12:43:04 am
content: The datasheet says it works as a switch that rattles off and on as it is moved. I don't use PICs. Is there an internal pullup on GP0 that you are relying on for the pullup? Why the resistor? Weak built in pullups are already very high resistance for a pullup and IMO should not be relied upon for this and you should have a proper external pullup.

author: Scutarius
author_rank: Regular Contributor
timestamp: April 20, 2010, 12:51:35 am
content: Yes, I use the internal pullup (weak) GP0herehttp://signalquest.com/datasheets/SQ-SEN-200%20App%20Circuits.pdfyou can see that they propose a 100k resistor.

author: TheDirty
author_rank: Frequent Contributor
timestamp: April 20, 2010, 01:17:26 am
content: You've actually got a hybrid of the flexible circuit, #1, and the Simple Circuit #2. If you are going to do the flexible circuit, you will need to do exactly what they did and use the two resistors plus the filtering cap. If you are using the simple circuit, it doesn't have R2 at all. It doesn't actually give a value for R1 in the simple circuit.

author: Scutarius
author_rank: Regular Contributor
timestamp: April 20, 2010, 01:39:43 am
content: you are right, tomorrow I will be testing the pcb with components, thanks I am going to make the correction.

author: Scutarius
author_rank: Regular Contributor
timestamp: April 21, 2010, 02:49:54 pm
content: I add a pin header for ICSP, just I want to be sure, if I do not use MCLR as MCLR, moreover I declared it as ouput, Can I just wire it to Vpp? (if not just a Resistor to Vcc with a diode for protection)Vpp is taken form my usb programmer so 5v it is also HVP?, I read that LVP is a pain, so I do not use this fuse, also it is important no to connect the battery while programming...I forgot to said that I am going to power it via 2 AA batteries, I did not choose the coin battery because of the LEDs (40mA total).http://www.instructables.com/id/Understanding-ICSP-for-PIC-Microcontrollers/