can anyone help me how to interface a thumbslide joystick with an atmega8
and also help me with the ADC code
and also help me with the ADC code
Welcome to Cemetech, Saransh123007! I can only assume that you saw my slide joystick to TI-calculator interfacing video (namely this one)? And can we safely assume that you're using this joystick from Sparkfun? As you can tell from that page, the pinout is:
1) x-axis output
2) +5V
3) y-axis output
4) gnd
They quoted me as saying: "Just to make sure I'm clear, my pin 4 is the one closest to the two screw/mounting holes. When connected to an Arduino, I get a range of about 128 to 775 on each axis, with enough consistency to check if it's at -x, center-x, +x, and -y, center-y, and +y."
May I ask what language you're writing? AVR ASM or C?
1) x-axis output
2) +5V
3) y-axis output
4) gnd
They quoted me as saying: "Just to make sure I'm clear, my pin 4 is the one closest to the two screw/mounting holes. When connected to an Arduino, I get a range of about 128 to 775 on each axis, with enough consistency to check if it's at -x, center-x, +x, and -y, center-y, and +y."
May I ask what language you're writing? AVR ASM or C?
i am using win avr . the joystick is form sparkfun . Yes, i saw your video with that calculator. Can you help me with this because it is my college project and i have never worked with adc module of atmega8 yet and the thumbslide joystick too
http://www.watterott.com/media/images/popup/09426-03.jpg
in this webpage there is a photo of the joystick so you mean to say that the pin which is lowest towards the gorund is the ground pin right ?
in this webpage there is a photo of the joystick so you mean to say that the pin which is lowest towards the gorund is the ground pin right ?
saransh123007 wrote:
http://www.watterott.com/media/images/popup/09426-03.jpg
in this webpage there is a photo of the joystick so you mean to say that the pin which is lowest towards the gorund is the ground pin right ?
The bottom pin in that photograph (closest to the two screw/mounting holes) is indeed GND. By the way, a point of etiquette on Cemetech: when it's less than 12 or 18 hours since your last post, edit your post instead of double-posting, please. So what is your main confusion, the hardware or the software side of things? in this webpage there is a photo of the joystick so you mean to say that the pin which is lowest towards the gorund is the ground pin right ?
okay sir will not double post . And i Want help for both hardware and software as in how should i connect the joystick to the port of an atmega8 and ADC programming to read it .
saransh123007 wrote:
okay sir will not double post . And i Want help for both hardware and software as in how should i connect the joystick to the port of an atmega8 and ADC programming to read it .
Well, let's take a look at a sample Atmega8 pinout:
I see six ADC inputs, namely pins PC0 through PC5. You need two inputs for the joystick (one for the X axis, one for the Y axis), so perhaps ADC0 and ADC1, or 23 and 24, respectively. The connections for Gnd and +5V on the joystick are hopefully obvious. I found a very simple ASM example for reading an ADC, but I have a feeling you want C, not ASM:
http://avrbeginners.net/architecture/adc/m8_adc_example.html
All the relevant information can be found in the ATmega8 datasheet under "Analog-to-Digital Converter". What have you tried? What are you having difficulty with?
thanks alot for your help and time . But should i connect the joystick directly without any resistors and capacitor ?
saransh123007 wrote:
thanks alot for your help and time . But should i connect the joystick directly without any resistors and capacitor ?
Yup, no need to put anything in between. Did you examine the two links that Benryves provided? Those should help you and help us help you. saransh123007 wrote:
yes i am examining it currently its a helpful source thank u
Excellent. Let us know if you have any new questions, and of course keep us updated on your progress.
can u help me with the break of 128 to 775 ie how do i know that suppose the joystick is in forward position then what will be the rating on y-axis (+ve direction) and what will be the data on the reverse side
saransh123007 wrote:
can u help me with the break of 128 to 775 ie how do i know that suppose the joystick is in forward position then what will be the rating on y-axis (+ve direction) and what will be the data on the reverse side
Welcome back, long time no see! I suppose you're referring to the bounds that I posted on the Sparkfun page? You can either do a high water / low water mark system if you're only interested in knowing forward and back, but you probably want forward, center, and back, correct? saransh123007 wrote:
yes i even want right and left also . what is watermark stuff can you enlighten me with it
The high watermark and low watermark concept deals with the fact that when you push to, say, +800, it only returns to, say, +500, and when you push to +100, it only returns to +400. Therefore, it's hard to tell where the center is. For forward and back, then you can say that going below +300 is foward, and the joystick remains in the forward position until it goes above +600, at which point it is in the back position. However, you want forward, back, and center, so you could say something like this, which is ripped straight from my code:
Code:
j = analogRead(xAxis);
if (j < 250) i = 1; //keyleft
if (j > 650) i = 2; //keyright
j = analogRead(yAxis);
if (j < 250) i = 4; //keyup
if (j > 650) i = 3; //keydown
if (i == 0) return;
ok thank you sir but i am using atmega8 in that i get values stored in adch and adcl where l- lower and h- higher register in this how does this no. get stored do have knowledge about it ?
saransh123007 wrote:
ok thank you sir but i am using atmega8 in that i get values stored in adch and adcl where l- lower and h- higher register in this how does this no. get stored do have knowledge about it ?
Well, I would take a look at how two-byte words are stored; there's lots of documentation on that. For example, 767 is $02FF, so h=$02, and l=$FF.
If using C, it's just a simple
Code:
Otherwise, you have to bear in mind the following:
Code:
uint16_t value = ADC;Otherwise, you have to bear in mind the following:
Quote:
When ADCL is read, the ADC Data Register is not updated until ADCH is read. Consequently, if the result is left adjusted and no more than 8-bit precision is required, it is sufficient to read ADCH. Otherwise, ADCL must be read first, then ADCH.
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