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About JimViau

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  • Birthday 12/08/1963

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    Electronic Robotic
  1. I have a PmodAD5 Analog to Digital converter capable of high precision with differential input capability. It use the Analog Device AD7193 ADC converter and also Analog Device ADR441 as an on-board 2.5 Vdc Voltage Reference. The Analog Device spec sheet for the ADR441 specify 2 different noise level for category A or B chip version. On the board, chip ADR441, one can read R02. I believe it is the Branding of the chip, like shown on page 18 of the spec sheet (but I am not sure if that's what it relate to). Though I am not aware what Branding means in this case. I am trying to determine if this ADR441 chip is of category A or B. According to the spec sheet, ADR441A would mean that the chip is a 10ppm/oC noise level, and ADR441B would be a 3ppm/oC noise level. Not that it would make a big difference for my project but I'd like to know what version in on my PmodAD5 board. Does anyone happen to know the information ? Thanks for your help
  2. My first post actually says, in fact, "JE is connected to the LS7366 counter via pins 1 2 3 4, SS3 SDO3 SDI3 SCK3". SS3 SD03 SDI3 and SCK3 are the PIC32 signal names, according to proMX7 Reference Manual. They are also called SS1A SDO1A SDI1A and SCK1A. If you look an page 18 and 19 of the Reference Manual, the SS3 SDO3 SDI3 and SCK3 are the names utilized to identify JE which is actually suppose to be referring to DSPI1 object from the DSPI library. The same Reference Manual is also identifying JF DSPI2 pins 1,2,3,4 named SS4 SDO4 SDI4 ans SCK4. But recently some updates on the UECIDE editor, the DSPI library as been modify to refer to DSPI2 as being implemented on JD and JF as been switched to DSPI0. I don't know why the switch but it's been a significant problem for my until I discovered by trial and error that the switch was implemented on the newest version uecide-0.8.8alpha22-windows-full. I hope the next time another version of UECIDE is published we get an advise concerning the switch back to JD DSPI0 JF DSPI2, if it ever comes back to the original disposition. Hope this clarify a few things. Regards
  3. 3V3 = 3.27V (metered) and the V5V = 5.16V, Neither voltages are dropping the slightest iota when I disconnect the USB cable. J3 is set to EXT, I am using an external PWM power supply from Fujifilm 5Vdc 1Amp. It's a well manufactured good quality power adapter meant to supply the 5V power to some electronic thing (don't remember). 1 Amp is plenty for my application. I the proMX7 board along with the LS7366 CMOS chip and an LED display. As for too much current draw on the SS pin, I am feeding the SS input pin of a CMOS LS7366 which, according to spec, will draw so little current that they did not even bother to measure, spec is listing 0 micro amp, so much for too big a load. One other peripheral is connected to JA pins 1,2,3 and is drawing some current out of the V5V. Current not measured but suspected to be about 100mA. It is a LED display. I use it to display the LS7366 counter value. I tried to take in and out to see if it's presence could make any difference... negative. Same signal drop at USB disconnection. I am using J2 USB with JP11 shorted. I've been using my board for learning how to program PIC32 so it's always been connected as such. Another thing, since I ported my sketch to address JD DSPI0 object instead of JE DSPI1, the problem has vanished completely. Since then, if I disconnect the USB cable the LS7366 keep responding without any interruption. When USB gets reconnected I do get a program reset, but that is just normal given the fact that JP11 is connected. This behavior is very weird. I think it's got to do with some internal idiosyncrasy within the ╬╝Controller. Or, perhaps and idiosyncrasy unique to my board. All ╬╝Controller are not necessarily coming out of the factory identical, I read that somewhere. If you find an explanation, I'd certainly be glad to hear about it. Thanks for your help.
  4. I have my proMX7 board running a very simple code that I adapted from Robogaia.com. I use the code to access an LS7366 Quadrature Counter and Rotary Encoder. The proMX7 is also driving an LKM1638 (8 digits LED driver board). I use the LKM1638 as a display output to read the LS7366 count value. Both peripherals are driven via SPI communication and using DSPI virtual object library. I am using two distinct ports, one for each peripheral. JA is connected to the LKM1638 display and JE is connected to the LS7366 counter via pins 1 2 3 4, SS3 SDO3 SDI3 SCK3. The code is very simple. I send a Read request to the LS7366, get the answer from the chip and send a little calculated value to the LKM1638. The calculated value appear on the display. I manually turn the encoder and I can see the actual value on the display change accordingly. It run smoothly and very accurately... until... Now the strangest thing happen when I want my proMX7 to run independently from the desktop computer I use for programming the board. So I just disconnect my USB wire from the computer and suddenly the LS7366 literally stop sending data through MISO->SDI3 ! I put my scope on both the digital outputs from JA to verify signal on the display and found no problem. I repeated the same test on the JE output pins 1 2 4 and found that the digital signal strength goes from 3.4Vpeak to as low as 2.7Vpeak. Obviously, 2.7V is not enough to drive the LS7366 counter, hence, no more output since it doesn't receive enough signal input. I have yet to build a circuit to correct the problem electronically ( transistor common base or something like that ). But, the question remains. Why is the SPI3 port looses signal strength when the USB is disconnected ? I know that internally, somehow, the UART is related to USB J2 on the proMX7. I am not knowledge enough to understand the intricate consequences about this relationship but I would certainly like to understand what is happening here. Is it possible that my proMX7 board is defective (I doubt it. Its been running fine for a while now ) ? Furthermore, why is the signal strength from JA is Not loosing strength when the USB from J2 is suddenly disconnected ? By the way, both LS7366 and LKM1638 are driven with JA and JE power pins 12 set to 5Vdc. I had trouble running the LKM1638 display at 3.3V and the LS7366 would run on 3.3V but my encoder would not, so I had to run the counter on the same Vcc as the encoder. I am actually stunned that the LS7366 is able to accept a 3.4Vpeak digital signal when powered with 5V, but hey! it works. Now, I am Not surprised the slightest bit that it wont work with a 2.7Vpeak signal strength. Besides the spec sheet clearly mention a minimum 3.5V logic high. So, the question remains: Why is the JE digital output strength looses 0.7V when the USB J2 is disconnected from the computer ? Is there a solution to this problem ? ( see documents attached ) Thanks for your help anyone ! LS7366MX7.ino LS7366 Quadrature_Counter LSI.pdf
  5. Cristian.Fatu thanks for this valuable information. I too am going in the plib direction with a code I got from http://hades.mech.northwestern.edu/index.php/Using_the_LS7366R_SPI_Quadrature_Counter (See bottom of page) These guys are using plib.h in a library to decode via SPI the infamous LS7366 Quadrature decoder. (no it's not infamous, It's a great chip actually, it's a fantastic chip!) Except that the code listed include the plib.h file. And since I am implementing this chip for further use, might as well do things correctly and up to date. Furthermore, my beginners ability in C++ is leading me to a brick wall for which I will need help to go over. So here is the question: How can I elegantly implement the code without the outdated plib.h ? Is there an updated version ? How would you do that ? What is the Microchip new way of replacing plib.h ? Appreciate your help
  6. I am new to PIC programming and recently purchased my first board pro MX7 with a PmodAD5 and a PmodDA2 and I am having a blast trying to program the stuff. Actually I am having a hard time for I am also new with C C++ programming. That being said, my current project is to implement a motorized linear displacement with a Load Cell and motor control and Position Encoder and get all this to perform some intelligent moves. So, I need to command my motor with the PmodDA2, Read the Load Cell with PmodAD5 and read my Quadrature Encoder with, ???, I don't know yet. I was looking at the LS7366 from LSI and then decided to look at the Pmod selection of modules. I am surprise to find no Pmod that can actually read an encoder? Or, did I missed it ? Implementing a Pmod-LS7366 module to add to the Digilent collection of modules would be convenient to us, beginners, who are not proficient enough to implement C code for quadrature reading. I know that Microchip controller are capable of such task. But I also read that it is better to implement the function into a separate hardware dedicated to the task and read the position value from that chip rather than implementing the code into the main controller. Risks of miss count are higher when the implementation is within the main controller. Besides, coding the main controller on top of my main application is quite a challenge for a beginner like me. So, here is my suggestion for Digilent: Make a Pmod-LS7366 with compatible Sketch and library. And if someone as a beginner solution for my Encoder Reading Needs, please advise... Regards
  7. JColvin, your answer to ltheoret concerning MPIDE link " (at least according to their wiki here)" I tried to go there to read. Nowhere on that page can I find the word MPIDE, Is that to correct link? Can you comment on this for I am quite new with my ChipKit pro MX7 board and just starting to learn how to program it. I'd like to know if I am going to invest some valuable time to learn an IDE might as well be one that is there to stay. Hence, I want to make sure I am not loosing my time with MPIDE if it is going to phase out eventually I will switch immediately to another IDE. What's your say on this? Should I switch now? Furthermore, Is there a good complete and precise source of training on how to use MPIDE. Other then how to install it, I cant find any more information. For instance, I am trying to find out exactly what the Tools/ Serial Monitor is and how to use it. Any information on that? thanks for your time Jim