I am working on a raw M5Stack multiApp firmware, based on @TomSuch M5StackSAM library, that include Oscilloscope, some WiFi tools, DHT, some games...

https://github.com/botofancalin/M5Stack_MultiApp_Firmware/tree/master/Precompiled_MultiFirmware

Its ALL made in one program and i still have LOTS of space to spare on the ESP32 flash memory.
Talking about the computing power... till now i use only one core. So all of this can run even on ESP8266 :)
I plan to add some heavy apps that will use the second core too.

The source code is available at https://github.com/botofancalin/M5Stack_MultiApp_Firmware

The project was eventually ported to Visual Studio with VisualMicro plugin

The project story:
The project was initially made on VS Code and PlatformIO - a very very nice IDE with a VERY fast compiler
Still... i had to fix the PlatformIO integrated ESP-IDF...
and today... the PlatformIO decided to stop working on VS Code (after a VS Code update).
Was still working fine on Atom...
Atom don't support intellisense so... i moved to Visual Studio and VisualMicro

I am open for sugestions what apps should i include into this project.
The ESP32 flash still have lot of free space.
At some time i added an Mp3 Player but i had trubles setting the volume on ESP DAC so i remove it till i find a solution

For now, i am planning to add Wifi Support (by user/pass and by WPS)

You can use hardwareSerial to assign (ex)Serial1 and Serial2 to different pin's then use Serial1 and Serial2 to communicate with the GSM and GPS

HardwareSerial Serial1;
Serial1.begin(unsigned long baud, uint32_t config=SERIAL_8N1, int8_t rxPin=x, int8_t txPin=y, bool invert=false);

Just an ideea...

Debugging Arduino on ESP32 using PlatformIO and GDB.
Debugging on M5Stack is not that easy because GPIO14 needed for JTAG is no easy accesible.
Will be very helpful to have an FTDI232H JTAG module option for M5Stack (maybe for M6Stack).
PlatformIO have a easy to use debugging option for ESP32.

"Just for fun"...

https://github.com/botofancalin/M5Stack-ESP32-Oscilloscope

a "Simple" 2 channel Oscilloscope, with Settings menu and 2 integrated signal generators

Ask 4 more :)

The solution is much easyer:

dacWrite (25,0);

Using this app, M5Stack can run all included apps without reflashing/rebooting

• This is the continued development of the original M5Stack MultiApp firmware
• This project is made on PlatformIO IDE
• With some minor work it can be adapted to other IDE's like VisualStudio+VisualMicro or Eclipse.
  This project use modifed M5Stack M5StackSAM and EspAudio libraryes from project local storage.
  image

Project Repository: https://github.com/botofancalin/M5Stack-MultiApp-Advanced

Get it going fast

• Flash your M5 with Precompiled firmware from this repository +The flashing instructions can be found on the Precompiled Firmware folder

Installing and Compiling the firmware

• First, you must install the necessary tools and prepare the IDE environment
• Download (and unzip) this repository
• Download and Install Visual Studio Code https://code.visualstudio.com/ or Atom: https://atom.io/
• Install the PlatformIO Extension
• Install ESP32 Framework on PlatformIO
• Apply the PlatformIO Patch
  -- This Patch will fix ESP-IDF bug - ButtonA Problems when Wifi is connected
  --This Patch will allow to upload large firmwares into M5Stack by sacrificing some SPIFFS area
  --Open the MultiApp Project folder on AplatformIO
• Click the BUILD button
  --This will build and Flash the M5Stack connected to your PC USB
• To use Local Ota to flash your M5Stack
  --The M5Stack must be connected to the same network as your PC
  --In the project "platformio.ini" file set "upload_port = [your M5StackIP]"

The project include:

• Applications
• Dual Channel Oscilloscope
  -- Pin 35 Channel 1
  -- Pin 36 Channel 2
  -- Pin 26 Signal Generator
• Oscilloscope Menu Structure:
  -- Stop / Run frame
  -- Sensitivity for each channel: 50mV, 100mV, 200mV, 500mV, 1V per Divizion
  -- Sample Rate: 0.3ms, 0.6ms, 1ms, 2ms, 5ms, 10ms, 20ms, 50ms, 0.1s, 0.2s, 0.5s, 1s, 2s, 5s, 10s per Divizion
  -- Channel mode for each channel: Normal, Inverted, Off
  -- Offset for each channel
  -- Trigger Switch: Trigger from Channel 1 or Channel 2
  -- Trigger Mode: Auto, Normal, Scan
  -- Trigger Level 0 - 100 %
  -- Trigger Edge: Rising (UP), Falling (DN)
  -- Internal Signal Generator mode: Wave signal, Square signal, Triangular Signal 1, Triangular Signal 2, Signal Generator OFF
  -- Exit Oscilloscope App
• WebRadio
  -- Support Volume Adjustment
  -- Support Stations change on the fly
  -- Long press NEXT key to exit from Radio App
  -- Display Volume Level
  -- Display Data buffer state
  -- If the connection is lost or the buffer get empty, will try to recover the connection.
  -- If the connection can't be recovered, will connect to the next station on the list
  -- Can play MP3 streams
  -- Web Radio streams are stored on SD Card on "RadioStations.txt" file
  -- Support theoretically unlimited station list
  -- The stations must be defined on separate lines as follow: "StationName=StationLink;
• WebServer with web based SD File manager
  -- Can run in the background once started
  -- You can use other apps when the webserver is running
  -- List SD Folders
  -- Create Folder
  -- Delete Folder
  -- Download files
  -- Upload Files
  -- Delete Files
  -- Display Files Content (images, text, etc...)
• SD Browser that support
  -- Display Jpeg files on the screen
  -- Resize Jpeg to fit to screen size
  -- Play MP3 Files using Mp3 Player App
  -- Display File properties for the files that can't be open with included apps
• Tools list
  -- Wifi Packet Monitor
  -- Wifi Scanner
  -- I2C Scanner
  -- DHT Sensor reader: Support any DHT sensor type
  -- Stopwatch
• Games (just for fun)
  -- Space Shooter
  -- Flappy Bird
• Return (to menu root)
• System
• System Informations
  -- CPU Frequency, Number of cores, Chip Revision, Flash Speed, Current Free RAM space, Wifi MAC address, Wifi IP Address, Wifi current Mode
  -- Minimum FREE heap (RAM) since the device was started, Flash Size, SPIFFS Size, SPIFFS used space, SD Card Type, SD Card Size, SD Card used space
• Wifi Connection
  -- Can set the Wifi Connection on M5Stack by
  -- Wifi Smart Config
  -- Wifi WPS PushButton
  -- Wifi WPS PIN Code
  -- Wifi STA: Set Wifi to STATION (Reciever) mode
  -- Wifi AP: Set Wifi to ACCESS POINT (Sender) mode
  -- Wifi OFF
• Display Backlight Settings
  -- Set and save Display backlight so the settings survive reboot and flash
• Sleep
  -- Puth the device into Sleep mode
  -- The device can power back on by pressing ButtonB or reset key

This Firmware also support:

• Local OTA flashing
  -- Set the M5Stack IP as Upload Port on PlatformIO then you can flash the device over WIFI
• Remote OTA Update
  -- Will check the server for new version at startup
  -- If a new version was found, will update to new version

M5Stack Weather Station was added to M5Stack MultiApp Advanced:
http://forum.m5stack.com/topic/194/m5stack-multiapp-advanced-firmware

add dacWrite(25,0); after M5.begin(); and the noise will be gone.

Make a voltage divider with 2 resistors (100k or so...) with one end connected to GND and the other end to 3.3v.
The middle of the divider connected to oscilloscope input pin.
Apply input signal to input pin and you get +/- 1.65v input range.
I designed the code to be used with this divider, that's why, without the divider, the oscilloscope line is at the bottom of the screen.
Once you connect the divider, the signal line will be at the middle of the screen just like on a normal oscilloscope.

The easyest way to start with ESP-IDF is by PlatformIO
That IDE include ESP-IDF, Arduino, Mbed...

@mrjellofingers

That noise is definitely related to your camera hardware or camera settings.
As you can see on the image from my post, there is no noise on the image with the camera i am using.

Added Loboris TFT DMA library.
This library improve the framerate on M5Stack TFT. Is 30ms faster for each frame.

The library is activated by macro -DUSE_DMA from platformio.ini

Here is a repository with 2 projects on it: https://github.com/botofancalin/ESP32_Camera_System.git

• A camera software for M5Stack camera
• A M5Stack software that can recieve the video stream from M5Stack camera and display it on the screen.

The projects can be compiled using PlatformIO

The camera stream can be accessed from browser too and can set various settings on it, while running:

You can mute the speaker very easy from code.
Just call
dacWrite (25,0);

@rop 在 Losing time? 中说：

I am writing an Arduino Time Library for ESP32. In the process of testing, I notice that the millis() counter on the M5Stack is fairly precise except it stops for 300 and sometimes 1300 ms all of a sudden, but only every once in a while. (maybe every 40 minutes so, but it seems to vary with what's running on it.) Does anyone (maybe at M5Stack?) have any idea what could be causing this?

Random odd behavior on various functions.
This is one of the reasons why i moved from arduino framework to ESP-IDF for my esp32 based projects...

@rop 在 M5ez, a complete interface builder system for the M5Stack as an Arduino library. Extremely easy to use. 中说：

@bobolink I haven't tried to convert any images myself, I have just taken the ones from Calin's code. I have been busy getting the new version out. I'll have a look at possibly creating a tool (or even an online tool) for this.

Open the file on HexWorkshop -> CTRL+A -> Edit -> Copy As -> C Source
Open the header file -> Paste :)

The solution is much easyer:

dacWrite (25,0);

• The images stored as array, take considerable space on the project.
• I recommend you to switch to PlatformIO for development.
  That IDE will give you a better look over the code objects and tier size. Just check the ".pioenvs" folder on the project.
  You can easy convert the code from PlatformIO for Arduino "IDE" .ino if you want to.
• avoid using "main" keyword on your code. Beginners may misunderstand that coding practice.
• avoid using preprocesor for class instances. Use "M5.Lcd.xxxx" instead "m5.lcd.xxxx".
  In some cases, it can save some ram this way (i know... is weird).

The list of components running on demo project is long... and you don't have control on all of them.
Most of them are from the framework. Arduino on its own is a memory hog:

The ez on itself don't use that much memory.
Here are the ez members that always reside in ram:

Beside those, there are M5 members, tft_eSPI members, Wifi members (that take a lot of space) and so on...
Those are the components with the most memory usage.

Here is a dependency graph for the demo project:

@rop 在 M5Go versus M5Stack 中说：

Question: do the 4MB of RAM eat noticeably more power?

No.
Is barely noticeable...

I can use a debugger on your code to see what's using the memory...
You can't use a jtag on M5Stack but you can make a setup similar to M5Stack and you can debug the code on that one.