Hi My friends , I hava done an application for Qtopia using QT . I can control pot on mini 2440 which is conntected to AIN0 . Value appears on screnn . İt is okey . But ı can't access to AIN1 pin . How to access AIN1 . May anyone help me please ...
Which kernel are you using?
Qtopia Version 2.2.0 , Z35 image used . How to learn kernel version . I am newbie about mini 2440 and linux
Sorrry not Z35 , it is T35
If the kernel (2.6.32.2) has been downloaded from here, as far as I am aware the other ADC channels are not enabled. You either have to patch the kernel or use a kernel that already the ADC (and GPIO and SPI already enabled). What are your learning or project objectives? Build from scratch or just develop applications?
I am trying to take analog value and grapt on screan . I have 3.5 inc mini 2440
Unless you find a tutorial that specifically does what you want I think you are in for quite a bit of work. Try this website: http://www.sereno-labs.com/what_happened_to_sereno-online Paolo does a graphing example using QT. You will have quite a bit work getting up to speed on QT. Then getting it running on the mini2440 is a fairly difficult task. Search for "mini2440vietnam" he has done some good tutorials. If I had to do this I would suggest starting with the Pengutronix BSP for this dev board (ADC and GPIO enabled) and go visit: http://wingston.workshopindia.com/wingz/embedded-programming-on-the-mini... Good luck!
Thank you davef , I can't understand topic at last link . I have qtopia on Mini 2440 , MY problem is not accessin AIN1 pin on GPIO. Now I have to solve this problem . I compile linux kernel , I load it to mini2440 but /sys/devices/platform/s3c24xx-adc/s3c-hwmon/in0_input is missing . I am very confused :(
Providing the "/sys/devices/platform/s3c24xx-adc/s3c-hwmon/*" is the job of the kernel. Search for how to enable the corresponding drivers in the kernel and how to register them in the board-file to make them occur at run-time.
Thanks Juergen , There is a many involution about this situation . I am newbie about linux and mini 2440 . How to search about what you say.I am confused .
Here are all my ADC notes.
Thanks dave , I have solved problem . I update adc.c in 2.6.32.2 kernel and compile the kernel . That is OK
hi......... i am also using the same pengutranix BSP i for qtopia i need to interface the External 24 bit ADC is it possible please help me.... if possible please refer some websites thanks in advance Nicky
Hi Nicky, There are a number of 24 bit ADC's out there and choice of interface too. I have used both SPI and I2C. SPI gives the fastest sampling time. How many channels do you need? You are going to have to develop something for this as there won't be anything ready to use with the Mini series of boards. I recently got a 16/18 bit ADC with 4 channels to work with Android and a Mini6410 board using I2C so it is possible. I designed my own PCB for this to include power and the I2C bus connection. It works very well and is stable. Another option you can consider is a 24 bit ADC with a small microcontroller with a serial port output. It all depends on how fast you want to sample the data at. Good luck. Dave...
Hi dave i need to interface only one channel from that i need to connect one sensor... otherwise please refer me how can i interface the onboard ADC and DAC? Thanks ==reg jack
Dave is a common name in this thread! What kind of DAC? I am currently building a break-out board with a SPI controlled 6 channel DAC on it. To drive the DAC you can patch the kernel for spidev, and then talk to the DAC with file write calls. There are several other more complex ways to do this. I can give you a spidev patch for 3.1 from Pengutronix and an example that is built in the local_src folder. The example drives a Mitsubishi M62354 6 channel DAC which has an unusual addressing structure, so may not be of a lot of use to you. It is untested. The Pengutronix BSP gives you access to AIN1, 2 and 3 out of the box. So, try building a kernel module example in local_src, there is already an example that comes in the template. Then, when you have got that going I could send the patch and example. Maybe, I will have it tested by then. davef
Keyword is: ptxdist newpackage src-linux-driver, type in ptxdist newpackage -help
Than you dave dac i am going to use Binary Weighted Ladder... But anyhow i am new to this pengutronix so, can you refer some good books or tutorials or website to develop...... i have already studied that oselas.BSP... file......... Regard Jack
The Quickstart guide is quite comprehensive. They have another publication which covers the generic PTXdist development process. Have you picked a specific DAC, binary weighted is the implementation type.
The test pot is a thru hole device. I take a soldering iron and remove it. Solder wires into the two holes for input and ground. It is the easiest way to get an analog input wired up.
hi Dave , please help me i know how to read the AIN0 using Penguttonix BSP, but now i need to interface one displacement sensor, in that i need to create on table that if ADC reads 2.7v it should show 0mm , 2.81-1mm,3.01v-2mm like that it will go,please help me to create like this Thanks in advance Regards Nicky jack
interface in AIN1 or 2 or 3
AIN1, 2 and 3 should be done the same way as AIN0. Are you asking me to write a C application to convert those values into something you can display on the screen using Qt or record these values in rrdtool or ?
Hi dave , I duno about rrdtool but my concept is even if my value is lies between 1.1mm or 1.2 or 1.3 mm ,1.5..... it should show... is it possible??? Thanks in advance Regards Nicky
Work out the resolution of a 10 bit ADC running off 3.3Volts and you find out how fine the steps could be. 3.3V/1014 bits = about 3mV increments. At 20mV/mm that tells me you will not be able to see a 0.1mm change. Maybe, 0.2mm. An op-amp with a 2.7Volt offset and some gain NIGHT get you better resolution. There will be a number of tolerance and drift issues to work through to determine if you will have the required accuracy. I think it is possible.
hi davef , That is correct but i going to use 24bit adc or 32 bit only suppose my sensor o/p is like this voltage displcement 2.5 1mm 2.71 2 2.81 3 3.01 4 3.50 5 4.10 6 if suppose my sensor reads 2.61,2.62,2.65,2.68,2.70volts it should show the corresponding intermediate between 1 and 2 mm ok, but i am not going to define the o/p volt in between the 1mm ,2mm,3mm etc, i just want to create one table and that should automatically generate the displacement in between that is it possible? Thanks in advance Regards Nicky
1 to 2mm is a 0.21 V step 2 to 3mm is a 0.1 V step 3 to 4mm is a 0.2 V step 4 to 5mm is a 0.49 V step 5 to 6mm is a 0.6 V step This does not look a very nice "curve" to try and fit a formulae to! Maybe, take smaller chunks and just do a linear interpolation between them until you get the results you want. I did some dual regression analysis years ago, but the "curves" were nicer than yours. Perhaps there are some newer or more relevant techniques for your job. Good luck!
Ah, you only want between 1 and 2mm, then fit a curve to it, ie dual regression analysis
ok thank you dave, will be able to develop using qt creator?
Have a look at sereno-on-line for a Qt example of a datalogger. If you want to display real-time graphs of what is happening than rrdtool might be useful.
step difference v voltage -0.256739854812620 3.262603044509890 1mm -0.262419700622560 3.519342899322510 2mm -0.235290527343750 3.781762599945070 3mm -0.276700973510740 4.017053127288820 4mm -0.219363212585450 4.293754100799560 5mm -0.277537345886230 4.513117313385000 6mm -0.228695392608640 4.790654659271240 7mm -0.267527103424080 5.019350051879880 8mm Hi dave please see this i got the good step difference i think now please tell me how can i prepare it like calibration sheet? and how do i set the reference voltage in mini 2440? Thanks in advance
The first thing I'd be asking myself is why the variable step difference between the various mm measurements, they are "all over the place". You are not going to be able to fit a curve to that data (just my opinion). Are you getting noise and/or do the readings vary over time? You might need to do a "running average" to get more consistent data. If the data is really like you have measured I would consider a LUT (look up table) and maybe linear interpolation between values. You will have to scale the voltage done so as not to exceed the max voltage rating of the ADC. Also, there is no point going to 15 decimal places! You have a 1024 bit ADC on the mini2440 with a max voltage of 3V0 or 3V3, check the datasheet.
A (little bit off topic) question of my interest in my only basic electronics knowledge: Is it possible to measure/generate voltages with a precision of 10E-15 with usual means? The values above confusing me... Thanks in advance, Titus