ElectronicsPosted by Morim Wed, May 07, 2008 11:36:56
Here is a sketch of the Tasks that will be used in my Altimeter. I have struggled a bit with defining the different Tasks, but now I think that it will work. A Task should be able to run independent of other Tasks. In some cases messages will be sent between tasks (dotted lines)
ElectronicsPosted by Morim Tue, April 29, 2008 11:38:09
I've bought a new C compiler from CCS yesterday. It is a complete IDE for C to the PIC. The Altimeter project has been in hold, waiting for this. Included is also a RTOS (Real Time Operating System), which I plan to use. Mostly because I want to try it.
CCS has a lot of HW support built in, and a good examples library, so hopefully I'll be up and running soon. The current code has to be ported from HiTech C to CCS, but that shouldn't be any problem.
ElectronicsPosted by Morim Sun, April 20, 2008 10:08:20
The routine for showing numbers on the display is now working.
Today we have a nice high pressure over Gothenburg. I will now go to Cape Hålanda to launch G-Zezz and Big daddy...
Next step is to get the menu working.
I will add two extra switches, so there will be one for "up" one for "down" and a "enter/ok" button..
ElectronicsPosted by Morim Thu, April 17, 2008 21:58:28
Finaly I got the 8x2 LCD working.
I had some problems first, but I solved it.
The contrast adjustment should be tied to "near ground" 0.3v - 0.0v, or else you wouldn't see anything...
The test loop simply puts an "x" to the display, clears the screen and the write an "x" again. Well, now I know that the LCD is working, and I can start doing some more serious programing. Like puting the barometric preassure in hPa and height above sea level on the screen :-)
That means some sort of clever conversion from 16bit value to a string of characters.
ElectronicsPosted by Morim Wed, April 09, 2008 21:27:58
Now the EEPROM is working as well :-)
The gray box is a socket for reading/writing the EEPROM. I'm using PICkit 2 for programming the PIC and EEPROM.
ElectronicsPosted by Morim Wed, April 09, 2008 11:33:59
I'm currently working on a new (barometric)altimeter.
It will sample preassuredata during the flight and store it on an 2kb EEPROM.
The data is taken from a MPX4115 preassure sensor, the value is converted by a 2chanel 12bit DAC (MCP3202) and a PIC16F690 is the "Brain". The program is written i C with HI-TECC C-compiler.
By using C I can use the logaritmic formula for calculating height (h=lg(p/P)*-7991)
This takes a lot of memory, but I'll will squeez as much as I can into the PIC.
It is still in very BETA version. The DAC is working (had some trouble setting up SPI communication) and the height calculating routines are also working.
Later I will start with the EEPROM routines and User interface and maybe connecting a 20g accelerometer to the circuit as well... :-)
And of course, build it on a circuitboard that will fit into the rockets!
Protoboard with (from left) EEPROM, DAC, MPX4115 PIC16F690
ElectronicsPosted by Morim Sun, March 09, 2008 20:15:01
This is a home built G-switch timer.
The G-switch is an ordinary microswitch with a M4 screw epoxied onto the leveler. By changeing the number of nuts, the trigger g-force can be set. Now I'll think its about 6G. After activating the switch, the timer will count to down to a pre set time, aprox 5-25sek before the igniter is lit. The current is on for .5s. when activated by g-switch a beeper will set of, and is active until battery is deattached.
The circuit has not yet been tested... :-)