Kindle brightness remote ( USB or Bluetooth )

Kindleschokolade · 12-10-2021, 06:05 AM

Hello,

I have some older kindles that I found for cheap in a thrift store and I would like to use them in an installation we are preparing.
For this to work as we are planning it, I 'd need to be able to control the kindle's brightness and power-on remotely.
Preferably via Bluetooth but I guess USB seems to be possible as well?
I have found Kindle Lazy ( https://github.com/llakssz/KindleLazy ) so far, but maybe there are some other ways as well?
As for the power-on, it might not work when the kindle is off but we are thinking about a mechanincally controlled magnet which would actuate the kindle magnet switch.
Thanks for all help!

katadelos · 12-10-2021, 03:49 PM

Not enough info here, we'd need to hear more about your intended use case before being able to assist more.

What model + firmware are your Kindles?
Are you planning on running the devices on battery power during your installation?
When you say "power-on", do you mean a cold start as in, first boot on a brand new device/completely dead device being charged or just waking the device up as a cover or the power button would do?
What connectivity options do you have at the site of your installation? If WiFi is an option, it wouldn't be difficult to create a simple server to control brightness over HTTP

Kindleschokolade · 12-10-2021, 06:17 PM

Hello and thanks for replying.
- The Kindles I have here are two jailbroken PW2s ( B0D4 ) with Fw 5.10.3
and one PW1 ( B024 )
- I was hoping to be able to run the devices on power from an usb power supply.
- The "power-on" would mean "waking up" like the cover or the button would do.
- The preferred connectivity would be wifi as I am planning to be able to read and display data ( letters and numbers ) from an udp connection as well, which I hope to be able to display on screen via a simple dynamic website or similar.
an option would be to connect the external brightness buttons via an arduino working as a mock usb-keyboard.

Thanks!

katadelos · 12-10-2021, 09:38 PM

I got bored and wrote a quick script that should handle your use case:

Code:

import subprocess
from http.server import *

class KindleLipcHandler(BaseHTTPRequestHandler):
    def _set_backlight_level(self, level):
        subprocess.run(
            f"lipc-set-prop com.lab126.powerd flIntensity {level}", 
            shell=True
        )

    def _get_backlight_level(self):
        level = subprocess.check_output(
            "lipc-get-prop com.lab126.powerd flIntensity", 
            shell=True
        )
        return int(level.strip().decode())

    def _wakeup(self):
        subprocess.run(
            "lipc-set-prop com.lab126.powerd wakeUp 1", 
            shell=True
        )

    def handle_backlight(self, path_tokens):
        action = path_tokens[-1]
        current_level = self._get_backlight_level()
        new_level = current_level

        if action == "up":
            if current_level < 24:
                new_level = current_level + 1
        elif action == "down":
            if current_level > 0:
                new_level = current_level - 1
        elif action.isdigit():
            if int(action) in range(0,25):
                new_level = int(action)

        if new_level != current_level:
            self._set_backlight_level(new_level)
            return 1

        return 0

    def handle_wake(self):
        self._wakeup()        
        return 1

    def do_GET(self):
        path_tokens = self.path.split("/")
        t_len = len(path_tokens)
        ret = 0
        if t_len == 3:
            if path_tokens[1] == "backlight":
                ret = self.handle_backlight(path_tokens)
        elif t_len == 2:
            if path_tokens[1] == "wake":
                ret = self.handle_wake()

        if ret:
            self.send_response(200)
        else:
            self.send_response(500)
        self.send_header("Content-type", "text/html")
        self.end_headers()

        if ret:
            res = "<html>OK</html>"
        else:
            res = "<html>FAIL</html>"
        self.wfile.write(res.encode())

def run(server_class=HTTPServer, handler_class=KindleLipcHandler):
    server_address = ('', 8000)
    httpd = server_class(server_address, handler_class)
    httpd.serve_forever()

run()

It provides a very simple API accessible over HTTP with the following endpoints:

http://{device_ip}/wake - Wake device from sleep
http://{device_ip}/brightness/up - Set brightness to next level up
http://{device_ip}/brightness/down - Set brightness to next level down
http://{device_ip}/brightness/{0,24} - Set brightness to specific level

To run it, install NiLuJe's build of Python3 from here, save the script above to /mnt/us/server.py and run nohup python3 /mnt/us/server.py & from a shell using SSH.

You'll probably need to open port 8000 on the firewall of the Kindle before you can call the endpoints over WiFi.

Kindleschokolade · 12-11-2021, 05:42 AM

Oh. Wow. Thanks so much.
As a general question:
I have experience with python, apache, linux and bsd but not with the kindle yet.
Is there a compendium of kindle-os specific info? so that I dont have to ask too many questions and can find out on my own?
my next step would be to connect to and read udp data and/or to connect to and read from signal k running on a raspberry on the same network.
Thanks a lot!

katadelos · 12-14-2021, 04:03 PM

Quote:

Originally Posted by Kindleschokolade

Oh. Wow. Thanks so much.
As a general question:
I have experience with python, apache, linux and bsd but not with the kindle yet.
Is there a compendium of kindle-os specific info? so that I dont have to ask too many questions and can find out on my own?
my next step would be to connect to and read udp data and/or to connect to and read from signal k running on a raspberry on the same network.
Thanks a lot!

There's no decent source of Kindle specific data apart from the forum itself; the wiki has bits and pieces but it's scattered about and is often severely outdated.

Broadly speaking, the Kindle OS consists of a (usually ancient) Linux kernel and a userland that would have been considered really modern circa ~2011. Reading a few books on embedded Linux from that era will give you a good idea of how things work internally.

lclrc · 12-16-2021, 09:56 PM

Quote:

Originally Posted by katadelos

I got bored and wrote a quick script that should handle your use case:

Code:

import subprocess
from http.server import *

class KindleLipcHandler(BaseHTTPRequestHandler):
    def _set_backlight_level(self, level):
        subprocess.run(
            f"lipc-set-prop com.lab126.powerd flIntensity {level}", 
            shell=True
        )

    def _get_backlight_level(self):
        level = subprocess.check_output(
            "lipc-get-prop com.lab126.powerd flIntensity", 
            shell=True
        )
        return int(level.strip().decode())

    def _wakeup(self):
        subprocess.run(
            "lipc-set-prop com.lab126.powerd wakeUp 1", 
            shell=True
        )

    def handle_backlight(self, path_tokens):
        action = path_tokens[-1]
        current_level = self._get_backlight_level()
        new_level = current_level

        if action == "up":
            if current_level < 24:
                new_level = current_level + 1
        elif action == "down":
            if current_level > 0:
                new_level = current_level - 1
        elif action.isdigit():
            if int(action) in range(0,25):
                new_level = int(action)

        if new_level != current_level:
            self._set_backlight_level(new_level)
            return 1

        return 0

    def handle_wake(self):
        self._wakeup()        
        return 1

    def do_GET(self):
        path_tokens = self.path.split("/")
        t_len = len(path_tokens)
        ret = 0
        if t_len == 3:
            if path_tokens[1] == "backlight":
                ret = self.handle_backlight(path_tokens)
        elif t_len == 2:
            if path_tokens[1] == "wake":
                ret = self.handle_wake()

        if ret:
            self.send_response(200)
        else:
            self.send_response(500)
        self.send_header("Content-type", "text/html")
        self.end_headers()

        if ret:
            res = "<html>OK</html>"
        else:
            res = "<html>FAIL</html>"
        self.wfile.write(res.encode())

def run(server_class=HTTPServer, handler_class=KindleLipcHandler):
    server_address = ('', 8000)
    httpd = server_class(server_address, handler_class)
    httpd.serve_forever()

run()

It provides a very simple API accessible over HTTP with the following endpoints:

http://{device_ip}/wake - Wake device from sleep
http://{device_ip}/brightness/up - Set brightness to next level up
http://{device_ip}/brightness/down - Set brightness to next level down
http://{device_ip}/brightness/{0,24} - Set brightness to specific level

To run it, install NiLuJe's build of Python3 from here, save the script above to /mnt/us/server.py and run nohup python3 /mnt/us/server.py & from a shell using SSH.

You'll probably need to open port 8000 on the firewall of the Kindle before you can call the endpoints over WiFi.

Good idea!

I use this method to turn pages and exec some other commands with remote dongle.

Kindleschokolade · 12-18-2021, 01:47 PM

Quote:

Originally Posted by katadelos

There's no decent source of Kindle specific data apart from the forum itself; the wiki has bits and pieces but it's scattered about and is often severely outdated.

Broadly speaking, the Kindle OS consists of a (usually ancient) Linux kernel and a userland that would have been considered really modern circa ~2011. Reading a few books on embedded Linux from that era will give you a good idea of how things work internally.

Thanks a lot. Will look into that then.

Kindleschokolade · 12-28-2021, 12:41 PM

Hello.
Finally came about to testing the script.
it works fine if the endpoint ist corrected to:
http://{device_ip}/backlight/
instead of
http://{device_ip}/brightness/

Thanks again!

Kindleschokolade · 12-28-2021, 12:48 PM

Also:
If I want to start this script on boot and keep it alive if it should crash, is this best done with cron?

12-10-2021, 06:05 AM	#1
Kindleschokolade Connoisseur Posts: 59 Karma: 14 Join Date: Dec 2021 Device: kindle PW3	Kindle brightness remote ( USB or Bluetooth ) Hello, I have some older kindles that I found for cheap in a thrift store and I would like to use them in an installation we are preparing. For this to work as we are planning it, I 'd need to be able to control the kindle's brightness and power-on remotely. Preferably via Bluetooth but I guess USB seems to be possible as well? I have found Kindle Lazy ( https://github.com/llakssz/KindleLazy ) so far, but maybe there are some other ways as well? As for the power-on, it might not work when the kindle is off but we are thinking about a mechanincally controlled magnet which would actuate the kindle magnet switch. Thanks for all help!

12-10-2021, 03:49 PM	#2
katadelos rm -rf / Posts: 219 Karma: 3333683 Join Date: Nov 2019 Location: United Kingdom Device: K5, KT, KT2, KT3, KT4, KV, PW2, PW3, PW4, PW5	Not enough info here, we'd need to hear more about your intended use case before being able to assist more. What model + firmware are your Kindles? Are you planning on running the devices on battery power during your installation? When you say "power-on", do you mean a cold start as in, first boot on a brand new device/completely dead device being charged or just waking the device up as a cover or the power button would do? What connectivity options do you have at the site of your installation? If WiFi is an option, it wouldn't be difficult to create a simple server to control brightness over HTTP

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12-10-2021, 06:17 PM	#3
Kindleschokolade Connoisseur Posts: 59 Karma: 14 Join Date: Dec 2021 Device: kindle PW3	Hello and thanks for replying. - The Kindles I have here are two jailbroken PW2s ( B0D4 ) with Fw 5.10.3 and one PW1 ( B024 ) - I was hoping to be able to run the devices on power from an usb power supply. - The "power-on" would mean "waking up" like the cover or the button would do. - The preferred connectivity would be wifi as I am planning to be able to read and display data ( letters and numbers ) from an udp connection as well, which I hope to be able to display on screen via a simple dynamic website or similar. an option would be to connect the external brightness buttons via an arduino working as a mock usb-keyboard. Thanks!

12-11-2021, 05:42 AM	#5
Kindleschokolade Connoisseur Posts: 59 Karma: 14 Join Date: Dec 2021 Device: kindle PW3	Oh. Wow. Thanks so much. As a general question: I have experience with python, apache, linux and bsd but not with the kindle yet. Is there a compendium of kindle-os specific info? so that I dont have to ask too many questions and can find out on my own? my next step would be to connect to and read udp data and/or to connect to and read from signal k running on a raspberry on the same network. Thanks a lot!

12-28-2021, 12:41 PM	#9
Kindleschokolade Connoisseur Posts: 59 Karma: 14 Join Date: Dec 2021 Device: kindle PW3	Hello. Finally came about to testing the script. it works fine if the endpoint ist corrected to: http://{device_ip}/backlight/ instead of http://{device_ip}/brightness/ Thanks again!

12-28-2021, 12:48 PM	#10
Kindleschokolade Connoisseur Posts: 59 Karma: 14 Join Date: Dec 2021 Device: kindle PW3	Also: If I want to start this script on boot and keep it alive if it should crash, is this best done with cron?