BattPulse

Contents

1. Introduction
2. CAN Bus Protocol — Overview
3. CAN Bus Protocol — Frame Reference
4. CAN Bus Protocol — Command Frame
5. CAN Bus Protocol — Code Examples
6. WiFi HTTP/JSON API — Overview
7. WiFi HTTP/JSON API — Endpoints
8. WiFi HTTP/JSON API — Code Examples
9. Data Model Reference
10. BattPulse Display Compatibility
11. Troubleshooting

1. Introduction

The BattPulse Leader BMS is a professional-grade, automotive-rated battery management system. It features a high-accuracy 16-bit analogue front-end for cell monitoring, high-current shunt-based current measurement, and a powerful dual-core microcontroller. It supports up to 126S lithium battery configurations (see product notes) with real-time cell monitoring, balancing, overcurrent protection, and multiple temperature probes.

The BMS exposes its telemetry data and accepts commands through two interfaces:

2. CAN Bus Protocol — Overview

Physical Layer

CAN Bus Connector

The CAN bus shares a connector with the shunt interface. See the Shunt and CAN Communication connector (Micro-Fit 3.0 — 43025-0600):

CAN ID Map

3. CAN Bus Protocol — Frame Reference

Byte:  [0]   [1]   [2]   [3]   [4]   [5]   [6]
Hex:   0x00  0x14  0x96  0x00  0x52  0x03  0x01
       <--5120-->  <--150--->  <--850--->  Status=Charging

Frame 0x350 raw bytes:
  Byte 0: 0x40  |  T1 = 320 (int16 LE) -> 32.0°C  (Die Temp)
  Byte 1: 0x01  |
  Byte 2: 0xBE  |  T2 = 190 (int16 LE) -> 19.0°C  (Shunt Temp)
  Byte 3: 0x00  |
  Byte 4: 0xB4  |  T3 = 180 (int16 LE) -> 18.0°C  (NTC_1)
  Byte 5: 0x00  |
  Byte 6: 0xBE  |  T4 = 190 (int16 LE) -> 19.0°C  (NTC_2)
  Byte 7: 0x00  |

4. CAN Bus Protocol — Command Frame

 External Device                  BattPulse BMS
  |                                |
  |-- 0x3A0 [01 52 53 54 52] --->|  ARM - armed state, 2s timer starts
  |                                |
  |     (within 2 seconds)         |
  |                                |
  |-- 0x3A0 [02 52 53 54 52] --->|  EXECUTE - BMS restarts!
  |                                |
  |        ~~~ BMS reboots ~~~     |
  |        (2-4 second gap)        |
  |                                |
  |<-- 0x300, 0x330, etc. --------|  BMS back online, CAN TX resumes

5. CAN Bus Protocol — Code Examples

Reading Pack Status from BMS (C / Embedded)

/* Parse a received 0x300 frame from the BattPulse Leader BMS.
 * Adapt to your CAN library and microcontroller platform. */

void parsePackStatus(const uint8_t *data, uint8_t dlc) {
    if (dlc < 7) return;

    uint16_t rawV   = data[0] | (data[1] << 8);   // little-endian
    int16_t  rawI   = data[2] | (data[3] << 8);
    uint16_t rawSOC = data[4] | (data[5] << 8);
    uint8_t  status = data[6];

    float packVoltage = rawV / 100.0;    // Volts
    float packCurrent = rawI / 10.0;     // Amps (+ = charging)
    float soc         = rawSOC / 10.0;   // Percent

    printf("Pack: %.2fV  %.1fA  SOC: %.1f%%  Status: %d\n",
           packVoltage, packCurrent, soc, status);
}

Sending a Restart Command to the BMS (C / Embedded)

/* Send the two-step ARM + EXECUTE restart command to the BMS.
 * Adapt to your CAN driver / controller. */

void sendBmsRestart() {
    can_frame_t cmd;
    memset(&cmd, 0, sizeof(cmd));
    cmd.id  = 0x3A0;
    cmd.dlc = 5;

    // Step 1: ARM
    cmd.data[0] = 0x01;    // ARM restart
    cmd.data[1] = 0x52;    // Safety key: 'R'
    cmd.data[2] = 0x53;    // Safety key: 'S'
    cmd.data[3] = 0x54;    // Safety key: 'T'
    cmd.data[4] = 0x52;    // Safety key: 'R'
    can_send(&cmd);

    delay_ms(200);  // Brief pause between steps

    // Step 2: EXECUTE
    cmd.data[0] = 0x02;    // EXECUTE restart
    can_send(&cmd);

    printf("Restart command sent - BMS will reboot in ~2-4 seconds\n");
}

Reading Cell Voltages (C / Embedded)

/* Parse cell voltage frames 0x330-0x337.
 * Call this for each received cell voltage frame. */

float cellVoltages[16];
int   cellCount = 0;

void parseCellVoltageFrame(uint16_t canId, const uint8_t *data) {
    int offset = canId - 0x330;
    if (offset < 0 || offset > 7) return;

    int cell1 = offset * 2;
    int cell2 = cell1 + 1;

    uint16_t raw1 = data[0] | (data[1] << 8);
    uint16_t raw2 = data[2] | (data[3] << 8);

    cellVoltages[cell1] = raw1 / 1000.0;  // Volts
    if (raw2 > 0) {
        cellVoltages[cell2] = raw2 / 1000.0;
        if (cell2 + 1 > cellCount) cellCount = cell2 + 1;
    } else {
        if (cell1 + 1 > cellCount) cellCount = cell1 + 1;
    }
}

6. WiFi HTTP/JSON API — Overview

The BattPulse Leader BMS runs a built-in web server on port 80. External devices (displays, dashboards, mobile apps) connect to the BMS WiFi network and poll the HTTP API.

The BMS supports these request types via the "type" field in the JSON body:

1. dashboard — returns pack status, temperatures, I/O states
2. cellStates — returns individual cell voltages and colours

7. WiFi HTTP/JSON API — Endpoints

POST /JsonHandle HTTP/1.1
Content-Type: text/plain

{"type":"dashboard"}

[{
  "type": "dashboard",
  "status": {
    "current": -12.5,
    "event": "Ready   ",
    "SoC": "%85",
    "PackV": "51.20",
    "MaxC": "3.65",
    "MinC": "3.60"
  },
  "TempProbes": {
    "Die Temp": 32,
    "ShuntTemp": 19,
    "Aux_1": 18,
    "Aux_2": 19
  },
  "IO_States": {
    "IN1": 0,
    "IN2": 0,
    "DO1": 1,
    "DO2": 1,
    "CHG": 1,
    "DSC": 1
  }
}]

POST /JsonHandle HTTP/1.1
Content-Type: text/plain

{"type":"cellStates"}

[{
  "type": "cellStates",
  "cells": {
    "Cell1": 3.650,
    "Cell2": 3.645,
    "Cell3": 3.660,
    "Cell4": 3.640,
    "Cell5": 3.655,
    "Cell6": 3.648,
    "Cell7": 3.652
  },
  "colors": {
    "1": "green",
    "2": "green",
    "3": "green",
    "4": "green",
    "5": "green",
    "6": "green",
    "7": "green"
  },
  "status": {
    "current": -12.5
  },
  "IO_States": {
    "IN1": 0,
    "IN2": 0,
    "DO1": 1,
    "DO2": 1,
    "CHG": 1,
    "DSC": 1
  }
}]

8. WiFi HTTP/JSON API — Code Examples

Polling Dashboard Data (Python)

import requests
import json

BMS_IP = "192.168.1.100"
URL = f"http://{BMS_IP}/JsonHandle"

# Get dashboard data
resp = requests.post(URL, data=json.dumps({"type": "dashboard"}))
data = resp.json()[0]

packV   = float(data["status"]["PackV"])
current = data["status"]["current"]
soc     = data["status"]["SoC"]

print(f"Pack: {packV}V  Current: {current}A  SOC: {soc}")

# Get cell voltages
resp = requests.post(URL, data=json.dumps({"type": "cellStates"}))
cells = resp.json()[0]["cells"]

for name, voltage in cells.items():
    print(f"  {name}: {voltage:.3f}V")

Polling Dashboard Data (C / Embedded HTTPClient)

/* Adapt this to your embedded HTTP client library. */

void pollBmsDashboard() {
    http_client_t http;
    http_init(&http, "http://192.168.1.100/JsonHandle");
    http_set_header(&http, "Content-Type", "text/plain");

    int code = http_post(&http, "{\"type\":\"dashboard\"}");
    if (code == 200) {
        const char* payload = http_get_response(&http);
        // Parse JSON response - first element of array
        // Extract status.current, status.SoC, status.PackV, etc.
        printf("Response: %s\n", payload);
    }
    http_close(&http);
}

9. Data Model Reference

BMS Data Fields

Physical Limits & Clamping

All values are clamped before CAN transmission to prevent invalid data:

10. BattPulse Display Compatibility

The BattPulse Leader BMS is natively compatible with the BattPulse BMS Display 7″. Both CAN and WiFi interfaces work out of the box:

11. Troubleshooting