Robot T1

Introduction

Partitions

The current partition scheme allows for (using a 4MB ESP32):

• two 1600 KB application partitions with OTA upgrade support
• 832 KB for a file system
• a nvs_keys partitions if/when NVS Encryption will be implemented

Camera images and power save

To save power, I am powering off the camera between pictures.

After power on the camera sensor needs time to compute AWB, AGC, AEC and other parameters for the current image.

First images after power on are green and dark then quality of images improves.

The time to compute those parameters depends of the current lighting conditions, image resolution and other parameters so using a fixed amount of time to wait is not a good practice.

To improve the image quality I have implemented the following algorithm:

1. power on the camera;
2. acquire an image and read ACG and AEC;
3. repeat the previous step until the AGC and AEC values are unchanged for a few consecutive readings. As a safety measure, the number of repeats is limited;
4. power off the camera.

With this algorithm the first good image is a little purple but the next ones are OK. This behavior may be related to sensor's temperature ?

Note: the implementation works for ov2640 sensor because I have added the functions to read the AEC and AGC manually in ESPCamera.cpp. The read functions should have been added to the esp32-camera library.

I2C

The first I2C controller is mapped to the GPIO15 as SCL and GPIO14 as SDA.

The camera uses the second I2C controller.

OTA Update

The firmware can be updated from a HTTP or a HTTPS server.

Security note

Warning: In the current version the content of credentials.h is added unencrypted in firmware. If you publish the firmware.bin file in a public location the credentials can be viewed easily by anyone who downloads the file.

OTA Update from a HTTP server, for development

For development I use the http.server python module to start a simple HTTP server like this:

# display your IP address
ip address show up

# allow acces to the HTTP server's port in firewall
firewall-cmd --zone=public --add-port=8000/tcp

# for python 3.7+
python3 -m http.server --directory ./firmware/
# for older versions of python 3 use `cd firmware && python3 -m http.server`

then send the update command to the bot:

/update http://yourIPaddress:8000/firmware.bin

OTA Update from GitHub

Send the update command to the bot with the full URL. As example, to load the RobotT1's published firmware use:

/update https://raw.githubusercontent.com/CalinRadoni/RobotT1/main/firmware/firmware.bin

OTA Update from a generic HTTPS server

Extract server's certificate in a C compatible output format. Here is one way to do it:

server="raw.githubusercontent.com"
echo | openssl s_client -showcerts -connect "$server":443 2>/dev/null | \
    sed -n '/-----BEGIN CERTIFICATE-----/,/-----END CERTIFICATE-----/H; /-----BEGIN CERTIFICATE-----/h; ${g;p};' | \
    sed 's/^/"/; $!s/$/\\n" \\/; $s/$/"/'

See the Extract certificates from a HTTPS server post for details regarding the previous code.

After you extracted the certificate it should be added to UpdateFromWeb.cpp and an entry for selecting it should be added to the UpdateFromWeb::SetCertificateForHost function.

Log level

In platformio.ini set CORE_DEBUG_LEVEL to a value according to ARDUHAL_LOG_LEVEL definitions from esp32-hal-log.h:

#define ARDUHAL_LOG_LEVEL_NONE       (0)
#define ARDUHAL_LOG_LEVEL_ERROR      (1)
#define ARDUHAL_LOG_LEVEL_WARN       (2)
#define ARDUHAL_LOG_LEVEL_INFO       (3)
#define ARDUHAL_LOG_LEVEL_DEBUG      (4)
#define ARDUHAL_LOG_LEVEL_VERBOSE    (5)

Note: if you want colors define CONFIG_ARDUHAL_LOG_COLORS as 1 in platformio.ini.

License

This repository is licensed under the terms of GNU GPLv3 license. See the LICENSE-GPLv3.txt file.