created for the TRMNL e-ink display.
graph TB
Start(["Start"])
Init("Init peripherals")
Start --> Init
IsLongRst{"Reset button
pressed > 300 ms?"}
Init --> IsLongRst
ClearWifi("Wi-Fi credentials clear")
IsLongRst -->|"Yes"| ClearWifi
DisplayInit("Display init")
IsLongRst -->|"No"| DisplayInit
ClearWifi --> DisplayInit
WakeReason{"Wake by
user or timer?"}
DisplayInit --> WakeReason
ClearDisplay("Display clear")
WakeReason -->|"User"| ClearDisplay
IsWiFiSetup{"Wi-Fi saved?"}
WakeReason -->|"Timer"| IsWiFiSetup
ClearDisplay --> IsWiFiSetup
NeedConfig("Show set-up message")
IsWiFiSetup -->|"No"| NeedConfig
%% Config Wifi
RunSetup("Start config portal")
NeedConfig --> RunSetup
IsReset1{"Device
reset?"}
RunSetup -->|"Yes"| IsReset1
WipeConfig1("API key, friendly ID and WiFi clear")
IsReset1 -->|"Yes"| WipeConfig1
Reboot1(["Reboot"])
WipeConfig1 --> Reboot1
IsWifiConnect{"WiFi
connected?"}
IsReset1 -->|"No"| IsWifiConnect
%% Main Body
TryConnect{"WiFi connected
(5tries)?"}
IsWiFiSetup -->|"Yes"| TryConnect
ConnectError("Show connection error")
IsWifiConnect -->|"No"| ConnectError
TryConnect -->|"No"| ConnectError
Sleep1(["Sleep"])
ConnectError --> Sleep1
ClockSync("Check synchronization")
IsWifiConnect -->|"Yes"| ClockSync
TryConnect -->|"Yes"| ClockSync
IsApiSetup{"API key and
friendly ID exist?"}
ClockSync --> IsApiSetup
%% Setup
CallSetup("Ping /api/setup")
IsApiSetup -->|"No"| CallSetup
IsSetupSuccess{"Setup
success?"}
CallSetup --> IsSetupSuccess
SetupError("Show setup error")
IsSetupSuccess --> SetupError
Sleep2(["Sleep"])
SetupError --> Sleep2
%% Check update
PingServer{"Ping server,
success?"}
IsApiSetup -->|"Yes"| PingServer
IsSetupSuccess -->|"Yes"| PingServer
PingError("Show server error")
PingServer -->|"No"| PingError
Sleep3(["Sleep"])
PingError --> Sleep3
%% Act on update
IsNeedReset{"Need to reset
the device?"}
PingServer -->|"Yes"| IsNeedReset
IsNeedReset -->|"Yes"| WipeConfig1
IsNeedUpdate{"Need to update?"}
IsNeedReset -->|"No"| IsNeedUpdate
IsNeedUpdate -->|"No"| Sleep3
Update("Download and update")
IsNeedUpdate -->|"Yes"| Update
Update --> Sleep3
following Wifi connection via the captive portal, device swaps its Mac Address for an API Key and Friendly ID from the server (which get saved on device).
GET /api/setup
headers = {
'ID' => 'XX:XX:XX:XX:XX' # mac adddress
}
response example (success):
{ "status": 200, "api_key": "2r--SahjsAKCFksVcped2Q", "friendly_id": "917F0B", "image_url": "https://usetrmnl.com/images/setup/setup-logo.bmp", "filename": "empty_state" }
response example (fail, device with this Mac Address not found)
{ "status" => 404, "api_key" => nil, "friendly_id" => nil, "image_url" => nil, "filename" => nil }
assuming the Setup endpoint responded successfully, future requests are made solely for image / display content:
GET /api/display
headers = {
'ID' => 'XX:XX:XX:XX',
'Access-Token' => '2r--SahjsAKCFksVcped2Q',
'Refresh-Rate' => '1800',
'Battery-Voltage' => '4.1',
'FW-Version' => '2.1.3',
'RSSI' => '-69'
}
response example (success, device found with this access token):
{
"status"=>0, # will be 202 if no user_id is attached to device
"image_url"=>"https://trmnl.s3.us-east-2.amazonaws.com/path-to-img.bmp",
"filename"=>"2024-09-20T00:00:00",
"update_firmware"=>false,
"firmware_url"=>nil,
"refresh_rate"=>"1800",
"reset_firmware"=>false
}
response example (success, device found AND needs soft reset):
{
"status"=>0,
"image_url"=>"https://trmnl.s3.us-east-2.amazonaws.com/path-to-img.bmp",
"filename"=>"name-of-img.bmp",
"update_firmware"=>false,
"firmware_url"=>nil,
"refresh_rate"=>"1800",
"reset_firmware"=>true
}
response example (success, device found AND needs firmware update):
{
"status"=>0,
"image_url"=>"https://trmnl.s3.us-east-2.amazonaws.com/path-to-img.bmp",
"filename"=>"name-of-img.bmp",
"update_firmware"=>true,
"firmware_url"=>"https://trmnl.s3.us-east-2.amazonaws.com/path-to-firmware.bin",
"refresh_rate"=>"1800",
"reset_firmware"=>false
}
response example (fail, device not found for this access token):
{"status"=>500, "error"=>"Device not found"}
if 'FW-Version' header != web server `Setting.firmware_download_url`, server will include absolute URL from which to download firmware.
if device detects an issue with response data from the api/display endpoint, logs are sent to server.
POST /api/logs
# example request tbd
Ths image displays the amount of power consumed during a work cycle that involves downloading and displaying images.
This image displays the amount of power consumed while in sleep mode.
This image displays the amount of power consumed during a work cycle that involves link pinging, new firmware downloading and OTA.
Full Power Cycle
- Sleep 0.1mA
- Image refresh cycle 32.8mA during 24s
If refreshed continuously, device will refresh 8,231 times (54 hours) on a full charge. If device is set to sleep continuously, it can sleep for 18,000 hours (750 days).
15 min refresh = 78 days 5 min refresh = 29 days
This image shows that the battery disconnects when the voltage reaches 2.75 V:
The pulse on the graph shows the voltage on the divider in sleep mode, further on the graph it can be seen that at the moment of disconnection of the battery on the divider under load the voltage is equal to 1V, i.e. a voltage of 1.2V under load on the divider can be considered extremely critical, which corresponds to a voltage of 1.5V in the state sleep on the divider and 3V on the battery:
See releases. For older versions go here.
A more user-friendly (and non developer) guide is available here: https://help.usetrmnl.com/en/articles/10271569-manually-flash-firmware
If you prefer to skip the build + upload steps below, flash directly from a web browser here: https://usetrmnl.com/flash.
- Install VS Code: https://code.visualstudio.com
- Install PlatformIO: https://platformio.org/install/ide?install=vscode
- Install Git: https://git-scm.com/book/en/v2/Appendix-A%3A-Git-in-Other-Environments-Git-in-Visual-Studio-Code
- Clone repository: https://github.com/usetrmnl/firmware
- After cloning, open project in VS Code workspace
- After configuring the project, click on the PlatformIO -> Build button located at the bottom of the screen
- After the compilation process is complete, you should expect to see a message in the console.
- You can find the compiled file in the folder shown in the picture.
-
Turn off PCB. Connect PCB to PC using USB-C cable. While holding down the boot button, turn on PCB. Let go of boot button. This puts board in flashing mode.
-
Mac/Windows: Select the proper COM port from drop-down list (or leave on "Auto"). Ubuntu: Look for something like "/dev/ttyACMO USB JTAG/serial debug unit" or "Espressif USB JTAG/serial debug unit" via lsusb.
- Click on "PlatformIO: Upload" button.
Tools required:
- Windows OS
- Flash Tool 3.9.5
- Firmware binary file
- Bootloader binary file
- Partition binary file
- Boot app binary file
open the Flash Tool (executable file), select these parameters, then clickOK:
- Beside the top blank space, click “...” dots and select the bootloader binary file then input
“0x00000000” in the far right space and check the box.
- Click “...” dots and select the partitions binary file then input
“0x00008000” in the far right space and check the box.
- Click “...” dots and select the boot_app0 binary file then input
“0x0000e000” in the far right space and check the box.
- Click “...” dots and select the firmware binary file then input
“0x00010000” in the far right space and check the box.
finally, set the following parameters at the bottom of the Flash Tool interface:
- Open the Windows “Device Manager” program and scroll to the bottom where the USB devices can be found. each machine will have different available devices, but look for a section like this:
-
Next, connect the PCB to the Windows machine with a USB-C cable. make sure the USB port is on the right, and that the PCB’s on/off switch is toggled DOWN for “off.”
-
While holding the BOOT button (below the on/off toggle), toggle the device ON by flipping the above switch UP. you may hear a sound from your Windows machine Inspect the Device Manager connections at the bottom of the interface, and a new device should appear. it may be “USB Component {{ Num }},” or something like below:
- Take note of this device’s name, that is our TRMNL PCB. then back inside the Flash Tool, click to open the “COM” dropdown in the bottom right and choose the TRMNL PCB. finally, click the “START” button.
Inside the Flash Tool click the “STOP” button.
Next turn off (toggle DOWN) and unplug the PCB. you are now ready to flash another device - see Step 1.
If you would like to run local tests, you'll need to have g++/gcc installed (f.e., as part of MinGW) in PATH:
- Get MinGW online installer from https://github.com/niXman/mingw-builds-binaries/
- Add path to
binfrom installed folder (f.e.c:\mingw64\bin) to your PATH - Restart Visual Studio Code
Now you can switch from "env:esp32..." to "esp:native" clicking at the bottom of the studio (point 1):
And then run platformio tests by clicking test button (point 2).
