Small, simple SAM G55 development board with extra functions
Block diagram
Features
Setting up the I2S DMA transfer with interrupt was not that straightforward, the datasheet is a little bit "tight-lipped" :-) ...and the official ASF example isn't commented good enough...
So my findings:
I started with the I2S example from the ASF 3.35.1 using Atmel Studio 7
In my opinion it works as expected, but You should be aware of some rules:
ATMEL freaks post: https://community.atmel.com/forum/samg55-i2s-dmapdc-endtx-interrupt-issue#comment-2327756
The original ASF example modified for mono transfer only:
x-labz
#include <asf.h>
#include <conf_test.h>
#include <string.h>
#define SOUND_SAMPLES 0x100
int16_t output_samples_left[SOUND_SAMPLES] = {
0x7F, 0x7F, 0x7D, 0x7E, 0x7D, 0x7E, 0x7D, 0x7E,
0x7D, 0x7D, 0x7D, 0x7F, 0x7E, 0x7D, 0x7E, 0x7D,
0x7D, 0x7D, 0x7C, 0x7A, 0x7B, 0x7C, 0x7A, 0x7A,
0x7C, 0x7B, 0x7E, 0x7F, 0x7F, 0x7F, 0x80, 0x80,
0x81, 0x82, 0x82, 0x83, 0x83, 0x83, 0x84, 0x84,
0x86, 0x83, 0x81, 0x81, 0x83, 0x83, 0x83, 0x84,
0x82, 0x84, 0x84, 0x83, 0x85, 0x85, 0x82, 0x83,
0x82, 0x82, 0x82, 0x82, 0x7F, 0x80, 0x81, 0x7E,
0x7E, 0x7E, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7E,
0x7C, 0x7E, 0x7E, 0x7F, 0x7F, 0x7D, 0x7D, 0x7C,
0x7D, 0x7D, 0x7D, 0x7B, 0x7C, 0x7B, 0x7C, 0x7D,
0x7E, 0x7E, 0x7F, 0x7E, 0x7D, 0x7F, 0x7E, 0x7D,
0x7D, 0x7B, 0x7D, 0x7D, 0x7E, 0x7D, 0x7D, 0x7E,
0x7D, 0x7D, 0x7D, 0x7E, 0x7E, 0x7C, 0x7E, 0x7E,
0x7F, 0x7F, 0x7E, 0x7E, 0x7F, 0x7F, 0x80, 0x81,
0x7F, 0x80, 0x81, 0x80, 0x81, 0x81, 0x81, 0x81,
0x82, 0x81, 0x82, 0x82, 0x81, 0x80, 0x7F, 0x80,
0x7F, 0x7F, 0x7E, 0x80, 0x81, 0x82, 0x83, 0x82,
0x83, 0x84, 0x81, 0x82, 0x82, 0x81, 0x82, 0x81,
0x80, 0x80, 0x82, 0x80, 0x80, 0x80, 0x80, 0x80,
0x80, 0x80, 0x7F, 0x80, 0x7F, 0x80, 0x81, 0x80,
0x80, 0x7F, 0x7F, 0x80, 0x81, 0x80, 0x80, 0x7E,
0x7E, 0x80, 0x7F, 0x7F, 0x80, 0x80, 0x7F, 0x7F,
0x80, 0x80, 0x81, 0x7E, 0x7F, 0x80, 0x7E, 0x7E,
0x7E, 0x7F, 0x7E, 0x7E, 0x7E, 0x7C, 0x7D, 0x7C,
0x81, 0x7D, 0x7C, 0x7C, 0x7B, 0x7D, 0x7C, 0x7D,
0x7D, 0x7D, 0x7B, 0x7D, 0x80, 0x80, 0x82, 0x80,
0x7F, 0x80, 0x83, 0x82, 0x80, 0x82, 0x84, 0x86,
0x86, 0x84, 0x84, 0x86, 0x87, 0x84, 0x85, 0x85,
0x85, 0x85, 0x86, 0x85, 0x85, 0x84, 0x83, 0x80,
0x81, 0x82, 0x83, 0x7F, 0x7E, 0x7F, 0x7F, 0x80,
0x7E, 0x7E, 0x7E, 0x7C, 0x7C, 0x7D, 0x7D, 0x7C
};
int16_t output_samples_right[SOUND_SAMPLES] = {
0x5A, 0x7F, 0x7D, 0x7E, 0x7D, 0x7E, 0x7D, 0x7E,
0x7D, 0x7D, 0x7D, 0x7F, 0x7E, 0x7D, 0x7E, 0x7D,
0x7D, 0x7D, 0x7C, 0x7A, 0x7B, 0x7C, 0x7A, 0x7A,
0x7C, 0x7B, 0x7E, 0x7F, 0x7F, 0x7F, 0x80, 0x80,
0x81, 0x82, 0x82, 0x83, 0x83, 0x83, 0x84, 0x84,
0x86, 0x83, 0x81, 0x81, 0x83, 0x83, 0x83, 0x84,
0x82, 0x84, 0x84, 0x83, 0x85, 0x85, 0x82, 0x83,
0x82, 0x82, 0x82, 0x82, 0x7F, 0x80, 0x81, 0x7E,
0x7E, 0x7E, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7E,
0x7C, 0x7E, 0x7E, 0x7F, 0x7F, 0x7D, 0x7D, 0x7C,
0x7D, 0x7D, 0x7D, 0x7B, 0x7C, 0x7B, 0x7C, 0x7D,
0x7E, 0x7E, 0x7F, 0x7E, 0x7D, 0x7F, 0x7E, 0x7D,
0x7D, 0x7B, 0x7D, 0x7D, 0x7E, 0x7D, 0x7D, 0x7E,
0x7D, 0x7D, 0x7D, 0x7E, 0x7E, 0x7C, 0x7E, 0x7E,
0x7F, 0x7F, 0x7E, 0x7E, 0x7F, 0x7F, 0x80, 0x81,
0x7F, 0x80, 0x81, 0x80, 0x81, 0x81, 0x81, 0x81,
0x82, 0x81, 0x82, 0x82, 0x81, 0x80, 0x7F, 0x80,
0x7F, 0x7F, 0x7E, 0x80, 0x81, 0x82, 0x83, 0x82,
0x83, 0x84, 0x81, 0x82, 0x82, 0x81, 0x82, 0x81,
0x80, 0x80, 0x82, 0x80, 0x80, 0x80, 0x80, 0x80,
0x80, 0x80, 0x7F, 0x80, 0x7F, 0x80, 0x81, 0x80,
0x80, 0x7F, 0x7F, 0x80, 0x81, 0x80, 0x80, 0x7E,
0x7E, 0x80, 0x7F, 0x7F, 0x80, 0x80, 0x7F, 0x7F,
0x80, 0x80, 0x81, 0x7E, 0x7F, 0x80, 0x7E, 0x7E,
0x7E, 0x7F, 0x7E, 0x7E, 0x7E, 0x7C, 0x7D, 0x7C,
0x81, 0x7D, 0x7C, 0x7C, 0x7B, 0x7D, 0x7C, 0x7D,
0x7D, 0x7D, 0x7B, 0x7D, 0x80, 0x80, 0x82...
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This experiment shows the overclocking results of the Atmel SAMG55 ARM Cortex M4F MCU.
The settings used:
- 3.3V supply voltage
- CPU clock from the external 32.768 KHz crystal multiplied by the internal PLL
- USB HID stack was running parallel
- 16K cache
- 5 flash wait states
- application runs from on-chip flash
- test application is the encoding + decoding of a 320 sample frame with CODEC2 700C algorithm (http://www.rowetel.com/?page_id=452)
The dataset:
| freq. | 120 MHz | 130 MHz | 140 MHz | 150 MHz | 160 MHz |
| encode + decode time | 28,5 ms | 26,5 ms | 25 ms | 23 ms | 21,5 ms |
120 MHz is the maximal CPU clock frequency allowed officially. The MCU was running stable at 160 MHz with continuous USB HID data communication.
The experiment shows, that 33% overclocking is still stable.
Here are some statistics of the cache performance. The MCU is an Atmel SAMG55 Cortex M4 with FPU.
The test algorithm is the state of the art CODEC2 voice coder (http://www.rowetel.com/?page_id=452)
The test application uses the 700C coding setting. The chart below shows the average encoding + decoding time in ms @ 120MHz with different cache size settings.
The dataset:
| noCache | 1K | 2K | 4K | 8K | 16K |
| 42 ms | 29,5 ms | 28,5 ms | 29,5 ms | 28,5 ms | 28,5 ms |
First heartbeat(s)
Atmel Software Framework (ASF) components work like charm!
maybe you can use pogo pin connector instead of the expensive SWD connector...
I too am working on a SAM G55 project. Am frustrated that the bootloader does not work over USB
I'd recommend to use an in system programmer / debugger, especially because of the debugger functionality.
This early version has some bugs, so no documentation will be published at the moment... Stay tuned! ;-)
Glenn Cameron
DoctorDre
Victoria
I want an easy way to test the product after it is assembled and NOT have assembly technicians use a debugger on the assembly line. Inserting a USB cable and looking for a CR response (as with SAM-BA) is easy to do with the Atmel E70. Don't know why Atmel didn't add USB to the bootloader code! Also the 10 pin SWD connector adds cost when already have USB!
Hope you add the schematic soon. Need to see if I am on the right track! Thanks!