@SirMichael
The issue you're encountering is due to differences in data alignment and padding between the Arduino NANO (AVR architecture) and the M5Stack Core2 (ESP32 architecture). Here's why the sizeof your structure differs and how to fix it:

Why the Size Differs

Data Alignment:

The ESP32 (Core2) aligns data to 4-byte boundaries by default for performance reasons, while the AVR (NANO) does not.
This causes the compiler to insert padding bytes between struct members to meet alignment requirements.

Double Precision (double):

On AVR, double is typically 4 bytes (same as float).
On ESP32, double is 8 bytes (true IEEE 754 double precision).
This alone explains part of the size difference.

Padding:

The ESP32 compiler may insert padding after uint16_t members to align the double to an 8-byte boundary.

How to Fix It
To ensure the struct has the same size and layout on both platforms, you can:

Use #pragma pack:

Force the compiler to use 1-byte alignment (no padding) for the struct:#pragma pack(push, 1) // Disable padding
struct AmpStruct {
uint8_t bMode;
uint16_t iBand;
float dVolts; // Use float instead of double for consistency
uint16_t iAmpTemp;
uint16_t iFanOutput;
uint16_t iFwdPower;
uint16_t iRefPower;
};
#pragma pack(pop) // Restore default alignment

Note: Replace double with float to ensure consistency (4 bytes on both platforms).

Manually Pad the Struct:

If you must use double, manually add padding to match the ESP32 layout:struct AmpStruct {
uint8_t bMode;
uint8_t _pad1; // Manual padding
uint16_t iBand;
double dVolts;
uint16_t iAmpTemp;
uint16_t iFanOutput;
uint16_t iFwdPower;
uint16_t iRefPower;
};

Use Serialization:

Instead of sending the raw struct, serialize it into a byte array with fixed sizes:uint8_t buffer[24]; // Adjust size as needed
buffer[0] = AmpData.bMode;
memcpy(&buffer[1], &AmpData.iBand, 2);
memcpy(&buffer[3], &AmpData.dVolts, 8); // Or use float
// ... repeat for other members
Serial.write(buffer, sizeof(buffer));

Key Takeaways

Use float instead of double unless you need the extra precision.
Force 1-byte alignment with #pragma pack to avoid padding.
Test the struct size on both platforms after changes:Serial.print("Size of AmpStruct: ");
Serial.println(sizeof(AmpStruct));

https://chat.m5stack.com/

There was an update for the UI and now i can burn an image to the AtomS3. Everything fine and thanks for your support and help!

Hi guys

corresponding github issue for reference.

It seems there isn't an easier way just (yet) than using Espressif Library Builder.

Thanks
Felix

@ajb2k3 Thanks.

@gwky55
Hi,
Example in MicroPython:

... def setup(): global wlan, http_req M5.begin() wlan = network.WLAN(network.STA_IF) if wlan.isconnected(): print('Connected') http_req = requests2.get('https://test/test.php?val1=aaa&val2=bbb', headers={'Content-Type': 'application/json'}) print(http_req.status_code)

And UI Flow2
http GET.png

@felmue This community website seems to have a problem with AI bots offering useless information as if they did not even read or understand the users question..

This is the second one in a few weeks.

@yuyun2000

This is the sketch i'm using.

/* * SPDX-FileCopyrightText: 2024 M5Stack Technology CO LTD * * SPDX-License-Identifier: MIT */ #include <M5GFX.h> #include <M5CoreS3.h> #include <FastLED.h> #include "UNIT_UHF_RFID.h" M5GFX display; M5Canvas canvas(&display); Unit_UHF_RFID uhf; #define LED_PIN 35 // GPIO pin for the NeoPixel LED #define NUM_LEDS 1 // Number of LEDs (1 for Core S3) CRGB leds[NUM_LEDS]; // Define the LED array String info = ""; void setup() { M5.begin(); // Init M5Core. 初始化 M5Core // Serial2.begin(unsigned long baud, uint32_t config, int8_t rxPin, int8_t // txPin, bool invert) uhf.begin(HardwareSerial *serial = &Serial2, int // baud=115200, uint8_t RX = 16, uint8_t TX = 17, bool debug = false); Serial2.begin(115200, SERIAL_8N1, 17, 18); uhf.begin(&Serial2, 115200, 17, 18, false); // uhf.begin(); while (1) { info = uhf.getVersion(); if (info != "ERROR") { Serial.println(info); break; } } String info = uhf.getVersion(); if (info != "ERROR") { Serial.println("UHF Module Connected. Version: " + info); } else { Serial.println("Failed to communicate with UHF Module!"); } // Initialize the NeoPixel LED FastLED.addLeds<WS2812, LED_PIN, GRB>(leds, NUM_LEDS); // Set the LED to green leds[0] = CRGB::Green; FastLED.show(); // max: 26dB uhf.setTxPower(2600); display.begin(); canvas.setColorDepth(1); // mono color canvas.setFont(&fonts::efontCN_14); canvas.createSprite(display.width(), display.height()); canvas.setTextSize(2); canvas.setPaletteColor(1, GREEN); canvas.setTextScroll(true); canvas.println(info); canvas.println("1.BtnB Polling Card EPC"); canvas.println("2.BtnC Select Card EPC"); canvas.println("3.BtnA Write or Read Card Info"); canvas.pushSprite(0, 0); Serial.println("Display initialized"); } uint8_t write_buffer[] = {0xab, 0xcd, 0xef, 0xdd}; uint8_t reade_buffer[4] = {0}; void log(String info) { Serial.println("Write Data..."); canvas.println(info); canvas.pushSprite(0, 0); } void loop() { if (M5.BtnA.wasPressed()) { log("Write Data..."); // uhf.writeCard(uint8_t *data, size_t size, uint8_t membank, uint16_t // sa, uint32_t access_password = 0); if (uhf.writeCard(write_buffer, sizeof(write_buffer), 0x04, 0, 0x00000000)) { log("Write OK"); } else { log("Write ERROR"); } delay(1000); log("Read Data..."); // uhf.readCard(uint8_t *data, size_t size, uint8_t membank, uint16_t // sa, uint32_t access_password = 0); if (uhf.readCard(reade_buffer, sizeof(reade_buffer), 0x04, 0, 0x00000000)) { log("Read OK"); log("Data Content"); for (uint8_t i = 0; i < sizeof(reade_buffer); i++) { Serial.printf("%x", reade_buffer[i]); canvas.printf("%x", reade_buffer[i]); } canvas.pushSprite(0, 0); } else { log("Read ERROR"); } } if (M5.BtnB.wasPressed()) { log("polling once"); uint8_t result = uhf.pollingOnce(); // polling 10 times // uint8_t result = uhf.pollingMultiple(20); Serial.printf("scan result: %d\r\n", result); if (result > 0) { for (uint8_t i = 0; i < result; i++) { log("pc: " + uhf.cards[i].pc_str); log("rssi: " + uhf.cards[i].rssi_str); log("epc: " + uhf.cards[i].epc_str); log("-----------------"); delay(10); } } } if (M5.BtnC.wasPressed()) { if (uhf.select(uhf.cards[0].epc)) { log("Select OK"); } else { log("Select ERROR"); } log("Current Select EPC:"); log(uhf.selectInfo()); } M5.

The sketch compiles perfectly fine and uploads to the device without error. this is the output.

Sketch uses 796606 bytes (25%) of program storage space. Maximum is 3145728 bytes. Global variables use 37948 bytes (11%) of dynamic memory, leaving 289732 bytes for local variables. Maximum is 327680 bytes. esptool.py v4.8.1 Serial port COM4 Connecting... Chip is ESP32-S3 (QFN56) (revision v0.2) Features: WiFi, BLE Crystal is 40MHz MAC: 24:ec:4a:38:34:98 Uploading stub... Running stub... Stub running... Changing baud rate to 921600 Changed. Configuring flash size... Flash will be erased from 0x00000000 to 0x00004fff... Flash will be erased from 0x00008000 to 0x00008fff... Flash will be erased from 0x0000e000 to 0x0000ffff... Flash will be erased from 0x00010000 to 0x000d2fff... Compressed 20208 bytes to 13058... Writing at 0x00000000... (100 %) Wrote 20208 bytes (13058 compressed) at 0x00000000 in 0.2 seconds (effective 865.4 kbit/s)... Hash of data verified. Compressed 3072 bytes to 144... Writing at 0x00008000... (100 %) Wrote 3072 bytes (144 compressed) at 0x00008000 in 0.0 seconds (effective 980.9 kbit/s)... Hash of data verified. Compressed 8192 bytes to 47... Writing at 0x0000e000... (100 %) Wrote 8192 bytes (47 compressed) at 0x0000e000 in 0.1 seconds (effective 1299.6 kbit/s)... Hash of data verified. Compressed 796752 bytes to 486375... Writing at 0x00010000... (3 %) Writing at 0x0001c618... (6 %) Writing at 0x0002181a... (10 %) Writing at 0x00026c91... (13 %) Writing at 0x0002c065... (16 %) Writing at 0x00031626... (20 %) Writing at 0x00036cfa... (23 %) Writing at 0x0003c073... (26 %) Writing at 0x00041262... (30 %) Writing at 0x000464a9... (33 %) Writing at 0x0004bdf3... (36 %) Writing at 0x00050f48... (40 %) Writing at 0x00056163... (43 %) Writing at 0x0005b41c... (46 %) Writing at 0x00061b58... (50 %) Writing at 0x00078b12... (53 %) Writing at 0x0007eb7e... (56 %) Writing at 0x00084ad7... (60 %) Writing at 0x0008a5e3... (63 %) Writing at 0x0008fa40... (66 %) Writing at 0x0009554d... (70 %) Writing at 0x0009ad33... (73 %) Writing at 0x000a05f6... (76 %) Writing at 0x000a5df1... (80 %) Writing at 0x000ab922... (83 %) Writing at 0x000b14ca... (86 %) Writing at 0x000b8d06... (90 %) Writing at 0x000c2507... (93 %) Writing at 0x000c86ae... (96 %) Writing at 0x000ce386... (100 %) Wrote 796752 bytes (486375 compressed) at 0x00010000 in 4.1 seconds (effective 1536.0 kbit/s)... Hash of data verified. Leaving... Hard resetting with RTC WDT...

When the upload has completed the device does nothing. No screen activity at all, it's powered on but just a blank display. I've tried everything, obviously i'm missing something, i just don't know what it is.

@kuriko
thank you.

Thank you everyone for all the messagges.

update>
I got it to work.
Spent many whours trying and playing with DIP, and was able to get it working bu using a FTL-UART board and connecting straight to U-blox, which was challenging since I dont have a windows pc and had to borrow one.

the main problem seems to be confusion with DIP, and cables.

thank you all for the help!!!!

I might "recover" this problem, althought I don't know why.
Only in japaness web page, you can find firmware of old version (But Its gone now....). When flesh back to old version , seems could solve this problem.here

@俺がガンダムだ said in LVGL performance problem:

I applied LVGL on stickc-plus2，with TFT_eSPI's st7789v2 driver.But the refreshing rate is very low (while doing "load screen anim").I know stickc had good performance on drawing screen (by watching the video of M5stick T-Lite Thermal tutorial). And the LVGL also has a good performance through Dial-ESP32-S3 and Din-Meter demonstration video.

So what is the reason of such low performance. Cound it be the TFT_eSPI library?

I’ve seen similar issues on the StickC-Plus2. It could be due to TFT_eSPI settings, try increasing the SPI frequency or enabling DMA. Also, check your LVGL buffer config; full buffering helps with performance.

The rom/miniz.h error occurs because newer board definitions (3.2.x) removed legacy ESP32 support. Downgrading to 2.1.x works, but to fix it permanently:

Manual fix: Replace #include <rom/miniz.h> with #include <miniz.h> in pngle.c (as noted in the linked guide). Disable auto-updates: In Arduino IDE, go to File > Preferences and uncheck "Check for updates on startup."

M5Stack isn’t abandoning older Cores, but newer SDKs drop deprecated APIs. If issues persist, stick with 2.1.x or modify the library.

@LeoZeLion
You can use the built-in API to use the functions of Base M5GO Bottom directly without additional blocky

@davidrubixbattery
The compilation errors you're encountering are related to the ESP32CAN library in the Arduino IDE. Specifically, the errors indicate that certain registers and definitions (DPORT_PERIP_CLK_EN_REG, CAN_TX_IDX, CAN_RX_IDX, and ETS_CAN_INTR_SOURCE) are not declared in the current version of the ESP32 Arduino core library you're using.
Steps to Resolve the Issue:

Update the ESP32 Arduino Core:

Ensure you are using the latest version of the ESP32 Arduino core. Open the Arduino IDE, go to Tools > Board > Boards Manager, search for "esp32", and update to the latest version.

Check the ESP32CAN Library:

The ESP32CAN library might not be compatible with the latest ESP32 Arduino core. Try using the M5Stack CAN library instead, as it is tailored for M5Stack products.

Alternative Library:

If the issue persists, consider using the ESP32 TWAI (CAN) API directly in your Arduino sketch. The TWAI API is the newer and recommended way to handle CAN communication on ESP32.

Verify Hardware Connections:

Ensure the Dial and Isolated CAN bus unit are correctly connected to the specified port (Port A) and that the pins are properly configured in your code.

Example Code for M5Stack CAN:
Here’s a basic example for initializing CAN on an M5Stack device:
#include <M5Stack.h>
#include "esp32_can.h"

void setup() {
M5.begin();
CAN_init(0, GPIO_NUM_5, GPIO_NUM_4); // Example pins for CAN TX and RX
}

void loop() {
// Your CAN communication logic here
}

Additional Resources:

M5Stack CAN Unit Documentation
ESP32 TWAI API Reference

https://chat.m5stack.com/