Emulate Dell chargers with ESP-01 module

dell.c

/*
 *    Example-Code that emulates a DS2502 - 1kbit EEPROM as a dell power supply
 *
 *    Tested with
 *    - dell notebook https://forum.pjrc.com/threads/33640-Teensy-2-OneWire-Slave
 *    - DS9490R-Master, atmega328@16MHz as Slave
 *    - Arduino ProMini clone
 *    - esp8266
 *
 *    OneWire messaging starts when AC adapter is plugged to notebook,
 *    try to use parasite powering but unfortunately it doesn't provide enough power,
 *    so You need DC-DC converter to power MCU
 *
 *    thanks to Nik / ploys for supplying traces of real data-traffic to figure out communication:
 *    - reset and presence detection normal
 *    - cmd from master: 0xCC -> skip rom, so there is only ONE device allowed on the bus
 *    - cmd from master: 0xF0 -> read memory
 *    - address request from master: 0x0008
 *    - master listens for data, gets CRC of seconds cmd and address first, then listens for 3 bytes, does not listen any further
 */

#include <Arduino.h>

#include "OneWireHub.h"
#include "DS2502.h"

// Valid for GPIO2 on ESP01 module
constexpr uint8_t pin_onewire   { 2 };

constexpr uint8_t charger130W[4] = {0x31, 0x33, 0x30};  //130W (=second digit of each hex-number)
constexpr uint8_t charger090W[4] = {0x30, 0x39, 0x30};  //90W
constexpr uint8_t charger065W[4] = {0x30, 0x36, 0x36};  //66W

// https://github.com/garyStofer/DS2502_DELL_PS/blob/master/DS2502_DELL_PS.ino
// constexpr const char* chargerEEPROMStr_90W = "DELL00AC090195046CN09T";

// https://nickschicht.wordpress.com/2009/07/15/dell-power-supply-fault/
constexpr const char* chargerEEPROMStr_90W = "DELL00AC090195046CN0C80234866161R23H8A03\x4D\x7C";
constexpr const char* chargerEEPROMStr_65W = "DELL00AC065195033CN05U0927161552F31B8A03\xBC\x8F";
// https://github.com/KivApple/dell-charger-emulator
constexpr const char* chargerEEPROMStr_45W = "DELL00AC045195023CN0CDF577243865Q27F2A05\x3D\x94";
// I made this up
constexpr const char* chargerEEPROMStr_130W = "DELL00AC130195067CN0CDF577243865Q27F2233\x9D\x72";

auto hub       = OneWireHub(pin_onewire);
auto dellCH    = DS2502( 0x28, 0x0D, 0x01, 0x08, 0x0B, 0x02, 0x0A); // address does not matter, laptop uses skipRom -> note that therefore only one slave device is allowed on the bus

// Assumes that serialStr is at least 40 bytes.
void crc(const char* serialStr, uint8_t* crc_l, uint8_t* crc_h) {
  uint32_t crc = 0;
  for (int offset = 0; offset < 40; offset++) {
    uint8_t byte = serialStr[offset];
    crc ^= byte;
    for (int i = 0; i<8; i++) {
      if (crc & 1)
        crc = (crc>>1) ^ 0xA001;
      else
        crc >>= 1;
    }
  }
  *crc_l = crc & 0xFF;
  *crc_h = (crc >> 8) & 0xFF;
}

void setup()
{
    //Serial.begin(115200);
    //Serial.println("OneWire-Hub DS2502 aka Dell Charger");
    //uint8_t crc_l, crc_h;
    //crc(chargerEEPROMStr_90W, &crc_l, &crc_h);
    //Serial.printf("CRC(90W)= %02X %02X !!!\n", crc_l, crc_h);

    // Setup OneWire
    hub.attach(dellCH);

    dellCH.writeMemory((uint8_t*)chargerEEPROMStr_130W, 42, 0);
    //dellCH.writeMemory(charger130W, sizeof(charger130W), 0x08);
}

void loop()
{
    // following function must be called periodically
    hub.poll();
}

Used the one from the OneWireHub examples and works great on my XPS 9550 :)

I'm writing this for prosperity : I got it to work using and arduino nano clone, what I had to do was connect the D2 pin (or the pin specified for one wire communication) to the dell ID directly WiTHOUT a pull up resistor, because anyway the dell laptop has a pull up to 3.3v on it's side...

I placed the arduino in my laptop (a 17 inch dell precision m6700 that had some free space inside as you can imagine) I connected the 5v always on power rail to the arduino ViN as it must be powered immediately when the charger is plugged in or else the charger won't be recognized.

You can look for the 5v always on in your laptop by using a multimeter and measuring capacitors, shutting down the laptop and removing the battery, then plug in the charger and power it on, the 5v always on power rail should not fluctuate at all when turning on the laptop and it should be present as soon as the charger is plugged in and the laptop is still turned off. You can also hunt down a schematic of your laptop and find the 5v always on like that.

Furthermore, I needed to emulate a 240w charger.
To emulate a charger of any wattage, you need to copy paste the 38th line, rename the variable to the wattage you need and modify the string so that is has the wattage and amps you need : as an example

constexpr const char* chargerEEPROMStr_90W = "DELL00AC090195046CN0C80234866161R23H8A03\x4D\x7C"
==> constexpr const char* chargerEEPROMStr_240W = "DELL00AC240195123CN0C80234866161R23H8A03\x4D\x7C"
See how I changed the watts from 090 to 240 as well as the amps from 04.6 to 12.3

Finally you need to modify the 76th line so that the arduino sends to the laptop the string of data that you created.

dellCH.writeMemory((uint8_t*)chargerEEPROMStr_130W, 42, 0);
==> dellCH.writeMemory((uint8_t*)chargerEEPROMStr_240W, 42, 0);

Thats it ! it should work for you hopefully !