Post by thread:[PIC:]Rocket camera timer

I'm currently building a mid sized camera rocket using a Kodak F-350 aps camera, it has an electronic shutter. I will be using two switches the first will engage very shortly after ignition and the second will make momentary contact when the chute opens. The first switch will start a program where a 1/2 second pulse will be triggered every 1.5 seconds for a total of 5 pulses then when the second switch engages the first program is bypassed and a second program starts a 1/2 second pulse every 5 seconds for a total of 5 pulses, then the chip shuts down regardless of any input. I'm very new with programming and have only programmed one pic with the blink program and it didnt work once put in the circuit, I have a few pic16F84A and have some 12F675 comming in soon. I have quite a bit of electronic knowledge, but programming is greek to me. Anything that would help would be great Mike -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

> I'm very new with programming and have only programmed one pic > with the blink program and it didnt work once put in the circuit, > I have a few pic16F84A and have some 12F675 comming in soon. I > have quite a bit of electronic knowledge, but programming is > greek to me. Maybe you should try and get your blink program working first? There are lots of great folks on here and I'm sure that they'll help you get it working... (I'll try myself, but I'm a bit of a beginner too!). I learnt so much by getting my first program working... Matt -- Matt N. Marsh Email: .....mattKILLspam@spam@mattmarsh.net Yahoo: marshmn Web: http://www.mattmarsh.net/ Jabber: mattmarshKILLspamjabber.org MSN: .....mattKILLspam.....mattmarsh.net ICQ: 250467363 AIM: MattMarshUK -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

This is a fairly simple project, so I don't think you'll have too much trouble. First, check the following site: http://www.voti.nl/swp/index.html The gentleman who authored it frequents the mailing list. Second, get the blinking circuit to work! Third, here's my approach: Use a 12F675 (since you have them). Run it with a 32.762 kHz crystal, since many are built to be sturdy and that's important. Use busy loops to wait the appropriate number of cycles (.5 sec is 4096 cycles). Ta-dah! Accurate to 20 ppm, and probably costs less that $2. If you need less accuracy, you can do it using the internal oscillator... Mike H. {Quote hidden}>I'm currently building a mid sized camera rocket using a Kodak F-350 aps >camera, it has an electronic shutter. I will be using two switches the >first >will engage very shortly after ignition and the second will make momentary >contact when the chute opens. > > The first switch will start a program where a 1/2 second pulse will be >triggered every 1.5 seconds for a total of 5 pulses then when the second >switch engages the first program is bypassed and a second program starts a >1/2 second pulse every 5 seconds for a total of 5 pulses, then the chip >shuts down regardless of any input. > >I'm very new with programming and have only programmed one pic with the >blink program and it didnt work once put in the circuit, I have a few >pic16F84A and have some 12F675 comming in soon. I have quite a bit of >electronic knowledge, but programming is greek to me. > >Anything that would help would be great >Mike > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email listservspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body _________________________________________________________________ FREE pop-up blocking with the new MSN Toolbar get it now! http://toolbar.msn.com/go/onm00200415ave/direct/01/ -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email @spam@listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> >I'm very new with programming and have only programmed one pic with the >blink program and it didnt work once put in the circuit, I have a few >pic16F84A and have some 12F675 comming in soon. I have quite a bit of >electronic knowledge, but programming is greek to me. As someone who has put computers in rockets before: Avoid crystals. Internal R/C oscillator, or external resonator is a much better choice. Xtals are internally fragile, and they don't like high accelerations. If you can keep the long axis of the crystal in the thrust line, they do a little better, but it's not worth it. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email KILLspamlistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> The first switch will start a program where a 1/2 second pulse As Matt Marsh has said, you really ought to get the chip working first otherwise any programming you do has got nowhere to go ---------------------------------- This is fairly simple in-line code that doesn't use interrupts. Not glamorous at all, but it's a pretty straight-forward job that doesn't require much sophistication. Note that it's untested and commits the PIC entirely to looping, which would not be the case if you used interrupts. But it's simple and hopefully you can follow it well enough to be able to build on Note also that "status,z" is not how most people would use the Zero flag, but it's clearer for you. It can be defined #define zero status,2 ;or status,z or tests made into macros, for example skpz macro ;skip next if Z=1 btfss status,2 endm MPLAB also allows the use of the BZ and BNZ branch instructions Anyway....... The timing of this is based on a 32.768kHz crystal, no pre-scaler, which will make TMR0 rollover 32 times / sec = (32768/4)/256 The 12F675 has a 16-bit TMR1, but the F84A doesn't. The F628 (F84A replacement) does too, but it hardly matters in this case. There are many ways to do what you want, this is just one. If you did use a 16-bit timer, then a /8 prescaler would produce 1/4s roll-overs, which would simplify the code. /16 is available for TMR0 to get 1/2s rollovers A couple of things you didn't specify. Are the switches toggle or momentary (you may need to test for switch release) and is the first timing period a pulse or a gap ? This code will do (pulse-space) x 5, repeat with modifications to do the second part clrf tmr0 ;initialise TMR0 movlw .5 ;initialise pulse counter movwf pulse_cnt clrf ro_cnt ;initialise rollover counter btfss switch1 ;wait for switch closure goto $-1 bsf pulse ;set output high initially ;hold pulse on for 1/2 second wait1 btfss intcon,t0if ;wait for TMR0 rollover goto wait1 bcf intcon,t0if incf ro_cnt ;increment rollover count movlw .16 ;test if = 16 = 1/2 second xorwf ro_cnt,w btfss status,z ;yes (zero flag = 1 = match) goto wait1 ;no bcf pulse ;set output low ;wait for 1 second clrf ro_cnt ;reset rollover counter wait2 btfss intcon,t0if ;wait for TMR0 rollover goto wait2 bcf intcon,t0if incf ro_cnt ;increment rollover count movlw .32 ;test if = 32 = 1 second xorwf ro_cnt,w btfss status,z ;yes goto wait2 ;no clrf ro_cnt ;reset rollover counter decfsz pulse_cnt ;bump pulse counter goto wait1 ;not done, repeat ;Part 2 btfss switch2 goto wait2 etc -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Mike, Check out http://www.xavien.com, they sale a nifty camera timer, I should know I designed it ;-). It even uses a PIC12C508A...... You can download the users manual to see the functions. Best regards, Steve >>> spamBeGonemrgizmospamBeGoneVIANET.CA 4/19/2004 5:08:10 PM >>> I'm currently building a mid sized camera rocket using a Kodak F-350 aps camera, it has an electronic shutter. I will be using two switches the first will engage very shortly after ignition and the second will make momentary contact when the chute opens. The first switch will start a program where a 1/2 second pulse will be triggered every 1.5 seconds for a total of 5 pulses then when the second switch engages the first program is bypassed and a second program starts a 1/2 second pulse every 5 seconds for a total of 5 pulses, then the chip shuts down regardless of any input. I'm very new with programming and have only programmed one pic with the blink program and it didnt work once put in the circuit, I have a few pic16F84A and have some 12F675 comming in soon. I have quite a bit of electronic knowledge, but programming is greek to me. Anything that would help would be great Mike -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email TakeThisOuTlistservEraseMEspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

I have made a camera timer to do pretty much exactly that take a look at http://www.robowars.org/teams/plan-b/Doonside%202003-06-28/ if you need help feel free to email me grooveee place the atsymbol here optushome .com .au MUHAHAAH choke on that spambots some general advice find out how the camera triggers ie for the camera I used it is active low inputs on its switches so triggering was easy. if your going to get a chip the 16F628A is a good one to get, the internal oscilator is a handy thing and good enough for what you want to do there (though all mine run at 20Mhz cos its just more fun ;->) and the built in USART makes debuging easy only experiment on and fly with a camera you dont mind recovering with a shovel. take a look at JAL it makes programming pretty easy for most things. {Original Message removed}

its all fairly well documented in the draft assignment on that page i believe basically the camera runs on 3.3V with the trigger and the buttons on the beack being active low inputs. the pic i was using was running on 5V basically all i did was set the pins that drove the camera to inputs (use the schmit trigger pins so there is no smoke) then set their outputs to low (while they were still set to input) then to trigger i made the pins outputs for a little while. ie pulling the cameras circut to ground. that was how my specific camera worked {Original Message removed}