I am having trouble making SDMMC work with DMA in 4 bit mode. I tried with FreeRTOS and without FreeRTOS didnt get anyresult. But it works perfectly without DMA.
It gives either Rx Overrun error or timeout error.
I tried it with different SD card, Different clock speeds, Different configuration no change.
I would really be grateful if someone can help me with this or have working example.
Thanks
Related
I'm trying to build a quadcopter flight controller from scratch using an ESP32, BNO055 IMU, and Turnigy TGY-i6 Transmitter/Receiver. So far I've been able to get everything to work together and give me reasonable data using PID control loops, filters, and various libraries. Previously I was using an Arduino Nano in place of the ESP32 because it was what I had at the time and I thought it worked well with it.
After doing some (very rough) flight testing I ended up coming to the conclusion that the code was not executing fast enough with the Nano to sustainably keep the quadcopter in the air. I decided to measure the loop time by setting a t1 and t2 at the beginning and end of the loop, and took the difference to find the time it took to execute one loop of the code. With the Nano, it took roughly 80000 microseconds exactly with little deviation.
Seeing this, I bought the ESP32 knowing that it had a much faster CPU clock speed and overall performance compared against the Nano. After getting the code to work on the ESP32 with a few changes, I ran a speed test again, and got the same 80ms. I was a bit confused at first but I decided to try and isolate the problem by taking out chunks of the code to see if the loop time would change - and it did not. After reading about some specific inefficencies of Arduino IDE [such as digitalWrite()] I kept trying to take away specific parts of the code, and no difference arose as I kept measuring the clock speed. It kept at roughly 80000 microseconds no matter the changes I made.
This leads me to believe that there is something quite important that I'm unaware about in my code that is causing it to run so slow. Ideally, I would like to be able to lower the loop time to at most 10ms so that the quadcopter can autolevel with little to no oscillation.
I've used Arduino for a few years now, but by no means am an expert - so any help on optimizing the code and/or solving this odd problem would be very much appreciated, Thank you.
Note: I have a suspicion that it may be something related to the IMU (BNO055) because that is one part of the hardware and software I know very little about.
These are the libraries I'm using:
#include "ESC.h" //ESC
#include <ESP32Servo.h> //ESC
#include <Wire.h>
#include <Adafruit_Sensor.h> //IMU
#include <Adafruit_BNO055.h> //IMU
#include <utility/imumaths.h> //IMU
#include <PID_v1.h> //PID
Here is the rest of the code.
After reviewing the code and segmenting it further, I discovered the problem was coming from the pulseIn() functions I use to read the PPM signal from the receiver.
The function works by:
Reads a pulse (either HIGH or LOW) on a pin. For example, if value is HIGH, pulseIn() waits for the pin to go from LOW to HIGH, starts timing, then waits for the pin to go LOW and stops timing. Returns the length of the pulse in microseconds or gives up and returns 0 if no complete pulse was received within the timeout. Link
Looking back, this clearly causes a delay in the code.
Thank you to dimich for putting me on the right path to solve the problem.
Edit: How you can solve this:
Rather than use pulseIn(), you can use interrupts to solve the problem. I did this by attaching an interrupt to the pin that is sending the PPM signal and listening for a CHANGE to happen on it. You then check whether the pin is HIGH or LOW and either begin or stop your timer. This avoids using delays in the program and allows for a clean signal to be read.
Note: Some receivers use a PPMsum on one pin rather than individual pins. On my receiver, I use 4 different channels and 4 different GPIO pins for each axis + throttle.
I am having an issue and looking for some ideas on what could be causing this problem.
I have a NodeMCU 1.0 that works fine and I am able to upload sketches using the Arduino IDE but if I have a SPI device plugged in, sketches will not upload. If I unplugged the device (I'm using pins GPIO 12-15 on the MCU) and then try to upload it works just fine.
As I've been troubleshooting this issue, I did notice that GPIO pins 13 and 15 are marked as RXD2 and TXD2 also so maybe that is related to my problem?
I would just keep working and unplug the device when I need to upload a new sketch but silly me just soldered in the SPI device and I really don't want to have to redo all my solder work.
Any guidance would be greatly appreciated.
So I got it working by grounding the select pin I was using, GPIO15. I think it may have something to do with what is mentioned here:
https://tttapa.github.io/ESP8266/Chap04%20-%20Microcontroller.html
But I don't quite understand why it worked.
I really want to make use of the SPI module on my NodeMCU. SPI keeps my code clean and frees up some of my GPIO pins. I feel it is sending data too fast for my 74HC595 to keep up with. It was working for a bit, then stopped.
It seemed like there was a lot of noise on the line so I hooked up the logic analyzer and saw that when I was sending data, bits were flying across the line at almost 6 ns (which is awesome). I am driving a 595 and ultimately a stepper, that need data at a way slower rate. I have tried using the clock parameter in the setup call, I feel it never slows the SPI clock.
Is there any way to set the clock speed to something that would be more 595+stepper friendly?
Just looking at the docs in the most recent dev branch of NodeMCU (get it from the NodeMCU Build website) you can setup SPI with a divider to lower the data rate of the SPI transmissions (higher div, lower bit rate):
spi.setup(id, mode, cpol, cpha, databits, clock_div[, duplex_mode])
Parameters include:
clock_div - SPI clock divider, f(SPI) = f(CPU) / clock_div
I am trying to use DMA for my UART Rx and Tx. Till now I had the freeRTOS version of the serial demo working fine. It still works fine. However, now I have incorporated the UART DMA example, from the example projects.
the code is conditionally compiled, so that when a switch _HAS_DMA == 1, only then the DMA engine is configured, ram buffers are configured, and default UART ISRs as required by the FreeRTOS demo are removed.
At this point, whenever I send a serial byte stream, the running project simply gets reset.
I am using MPLAB IDE 8.92, XC16 v1.20, Explorer-16 platform, dspic33fj256gp710 part.
The DMA code included does not use any FreeRTOS API calls.
I have setup the project so that StackOverflow is detected using the FreeRTOS configuration option. But the code does not reach the Stackoverflow hook function. I have also included the U2ErrInterrupt ISR to see if incoming bytes are coming in fine, however even that interrupt is not reached.
Has any one faced this before?
interestingly, the UART DMA Loopback example from Microchip website, which uses the MPLAB C30 compiler, works fine on my board.
any pointers on this one? I could not locate any code examples in the FreeRTOS forum on how to use the DMA for UART, but it is suggested to use this method in production code for efficiency.
Need help here.
Thanks and best regards,
Vishal
OK. I found the culprit. Its me. :)).
When setting up the DMA to receive UART interrupts, one should not enable UART interrupt separately in software. Which is what I was doing. In addition, I had conditionally un-compiled the UART ISRs from my code !!!. So in effect, whenever a byte was received by the UART engine, the processor is getting confused as to who will serve this interrupt, DMA or Application code. I thing the PC would point to the designated UART RX ISR vector location, where the processor would not find anything, and this was causing the reset. Or may be there was a race condition setup between the DMA and the processor to serve this interrupt, which was causing the reset.
Now that I have setup UART so that Interrupts are not enabled separately by application, when DMA is going to serve the UART RX, my code is working fine. I am yet to integrate the whole thing with FreeRTOS deferred interrupt processing using binary semaphores, but I hope I will not see any troubles there.
There is not much documented about this though...neither in Microchip manuals nor in the FreeRTOS examples.
Also, I found that when using DMA with UART, as per the manual, the DMA receives WORDS from the UART RX engine, with lower byte having the data, and upper byte having the status. If the DMA is also used for UART Tx, and is set to transfer WORDS to UART TXREG, the two intelligently manage to send only the lower data byte out. So the receiving party still gets expected bytes. This is also not documented well.
I will try to post my code here for future generations though :)).
I'm porting u-boot-2013.10 to MPC8306 based board. Previously, I can erase the first several sectors of Nor Flash using BDI2000. But after sometime, when the porting task is nearly done, (I mean that I can use gdb to trace the code execution and find the u-boot code runs into command line mainloop, though there are no serial output at the time, due to error configure of Serial Port)the first 256KB of Nor Flash can't be erased even if after power off reset. Other sectors can be erased normally.
The Nor Flash is Micron M29W256GL, with block size 128KB. I'm sure the WP# Pin has been pulled high, so there is no hardware protection upon the first block.
When config the jumper on board to change the PowerPC Config Word in order not to let MPC8306 fetch boot code at power up, the problem remains.
I used to run u-boot-1.1.6 on this board, I have erased this version of u-boot so many times without the problem mentioned above. I guess u-boot-2013.10 made some new approach to flash manipulation or others, for example, non-volatile protection on first 256KB of flash.
Is there someone can help me to solve the problem? I would very much appreciate your help.