xplain | Interactive demos | Data Visualization library

I can't seem to figure out how to send a pointer to a struct using a queue in FreeRTOS. I've tried all I could think of, yet I always get a pointer to some random region of memory.

I'm trying to send a pointer to a button struct to another task, where it will then be drawn on the screen. I tried sending the whole object and it worked, but since there's a lot of data in the struct (data of two icons) I don't really want to do that.

The code is being run in Atmel SAME70 Xplained.

Here is a simpler version of the code I'm working on:

I am following Bootlin's embedded Linux training which aims to put an embedded Linux system on an Atmel SAMA5D4 Xplained board (theory slides, practical lab instructions) and I am stuck a putting the whole system on the NAND flash.

They ask me to put the DTB, the kernel, the root filesystem and a data filesystem in a UBI image to be written to the flash but I cannot access the UBI partitions once I flashed it (the access fails with error code 22, or -22 in an embedded Linux environment).

(to see my actual questions, go to the end of the question)

In U-Boot, the partitions are defined by mtdparts:

(I am really unsure of which tags to apply, so apologies in advance if I chose the wrong ones.)

I hope that this is not a too stupid question, but I'm really lost here.

A client lent me an Atmel SAMA5D2 Xplained board with Linux4SAM to play around with. I'm trying to interface the SPI interface on it, but I have no clue where to start.

To be clear, I've used similar boards (not this particular one) bare-metal. I've also used Linux for many years and wrote a few simple devices drivers some years ago. And still I'm lost.

dmesg | grep spi gives me the following output:

I'm a beginner with programming AVR devices, in an attempt to move away from the inefficient _ms_delay() and _us_delay() blocking functions I've been trying program using the built in timers to control the timing of a basic LED flashing program with the CTC timer mode on a 16-bit timer. My goal is to make the LED flash at 2 Hz, on for 0.5s, off for 0.5s.

According to the ATMega328P datasheet, the freqency of a CTC output should be f_CTC = f_Clock/(2N(OCR1A+1), since my chip is a 328P Xplained mini, it's default CPU speed is 16 MHz, using the above formula, with N=64, the required OCR1A value to achieve my desired frequency should be 62499. With all of this in mind I wrote the following code:

I'm struggling with timer 1 configuration of the SAM4SD32C of the XPlained Pro Sam4s Board... I first used timer 0 and I could generate the waveform I needed.

So I copied past the code, adapted it for timer 1 to generate other waveform following the same technique. While debugging I noticed I couldn't get into my Interrupt routine. I inspected further and noticed that I couldn't write into Register RA and RC of timer 1 using tc_write_ra() and tc_write_rc() functions.

Here's part of my code, which I considered could help answering my problem. If more code is needed, then ask in comments.

I'm working on a freeRTOS project and the SAM4S Xplained Pro.

In a task called every x ms, I would like to:

• initiate transmission of datas
• extract data from a reception buffer (if an end of frame has been detected)

I'm wandering if there is a way to wake up this task not only periodically, but also when an end of frame has been detected ? And when this task is woken up by this event, only extraction of data would be performed, not the data transmission.

Is the best way consists in creating two tasks ? One for emission, other for reception. I've not writen any code yet, I'm looking for some advices on how to deal with FreeRTOS and communication issues, as I'm a begginer in it...

I'm trying to use USART 0 on the SAM4SD16C processor. I got some help to start, from this website : SAM4S Xplained USART

Here's the code I'm using (which compiles):

When I call vTaskDelay, the delay lasts half of the supposed time. I have traced back the problem and I see that the Tick rate value is the double of what it should be as defined in configTICK_RATE_HZ. I checked this using the tick hook to toggle a led and measuring the frequency with an oscilloscope.

I am configuring the Atmel SAM L21 Xplained pro A board (ATSAML21J18A), with Atmel Studio 7 and FreeRTOS v8.0.1, based on the files of an ASF example called "FreeRTOS tickless demo using OLED1 Xplained".

My CPU clock runs at 12MHz from the SYSTEM_CLOCK_SOURCE_OSC16M. The configured tick rate is 100 Hz, from a timer clocked from GLCK_O(CPU clock). However, when I change the CPU clock rate at 4MHz instead 12 MHz, the Tick rate is correct, so I guess I'm missing some configuration somewhere for the timer which runs the OS tick.

Here are some values of OS tick rate I get with different CPU clock rates:

• CPU: 4 MHz - Tick rate: 100 Hz
• CPU: 8 MHz - Tick rate: 548 Hz
• CPU: 12 MHz - Tick rate: 218 Hz
• CPU: 16 MHz - Tick rate: 548 Hz
• CPU: 48 MHz - Tick rate: 2,25 kHz

Also, when I configure the OS tick timer clock source as the internal ultra low power oscilator ULPOSC32k running at 32kHz, the tick rate is correct, independently of the CPU clock frequency (100Hz).

Moreover, when I select tickless mode (1 or 2), even with the configuration that works well in tick mode, with the CPU at 4MHz and the tick interrupt generated from the Systick timer, I have the same problem, the dalay lasts half of what it should.

In FreeRTOSConfig I have:

I want to make a interrupt driven uart program, to send large amounts of data at high speeds with the absolute minimal amount of cpu overhead. I combined existing code and reading of the datasheet to make this code. It compiles without errors or warnings in Atmel Studio 7 on an atmega328p (Atmega328p Xplained Mini).

The problem that I'm having is that data is erratic, sometimes it sends 'ello!' sometimes nothing for a while. The 'H' is often skipped, I don't understand this since the ISR shouldn't execute before the 'H' has been copied from UDR0 to be sent.

Any help would be greatly appreciated!

Greetings,

Bert.