Flatpack2 CAN Controller using ESP32

Hardware Components

• ESP32 Dev Board
• CAN transceiver (either one):
• • SN65HVD230 (3.3V)
• • TJA1051T/3 (with 5V booster)
• 2x 120Ω resistors (bus termination)
• Length of 2 wire twisted cable (pair of CAT5E works great)

Detailed Connections

1. Schematic

+- (5V) USB Power
+-----------------+      +------------------+      +---------------------+
|      ESP32      |      | SN65HVD230 Board |      |   Flatpack2 PSU     |
|                 |      |                  |      |                     |
|                 |      |                  |      |              AC (L) |
|                 |      |                  |      |              AC (N) |
|           3.3V  | ---- | 3.3V    +- CAN_H | ---- | CAN_H -+            |
|                 |      |        120Ω      |      |       120Ω          |
|                 |      |         +- CAN_L | ---- | CAN_L -+            |
|   GPIO 17 (TX2) | ---- | TX               |      |                     |
|   GPIO 16 (RX2) | ---- | RX               |      |                     |
|                 |      |                  |      |             DC +48V |
|            GND  | ---- | GND              |      |             DC -48V |
|                 |      |                  |      |                     |
+-----------------+      +------------------+      +---------------------+

Important

2x 120Ω resistors: On each end of CAN twisted cable connecting CAN_H to CAN_L

Tip

If using TJA1051T/3 (Adafruit CAN PAL) connections stay the same, just connect SLNT (S) pin to GND

Warning

Please note that -48V is not connected to tranceiver or ESP32!

2. Setup

ESP-IDF Configuration

#define TWAI_TX_PIN GPIO_NUM_17
#define TWAI_RX_PIN GPIO_NUM_16

twai_general_config_t g_config = {
   .mode = TWAI_MODE_NORMAL,
   .tx_io = TWAI_TX_PIN,
   .rx_io = TWAI_RX_PIN,
   .clkout_io = TWAI_IO_UNUSED,
   .bus_off_io = TWAI_IO_UNUSED,
   .tx_queue_len = 10,
   .rx_queue_len = 10,
   .alerts_enabled = TWAI_ALERT_NONE,
   .clkout_divider = 0
};

twai_timing_config_t t_config = TWAI_TIMING_CONFIG_125KBITS();
twai_filter_config_t f_config = TWAI_FILTER_CONFIG_ACCEPT_ALL();

Commands via Serial

Current project has the ability to control flatpack2 via serial:

echo -ne '<CTFP,SET,4320,100,5800>' >/dev/ttyUSB0
echo -ne '<CTFP,DEF,5410>' >/dev/ttyUSB0

• <CTFP, Start of message
• SET/DEF: SET_OPERATION/DEFAULT_VOLTAGE
• • SET VOLTAGE,CURRENT,PROTECTION
• • DEF VOLTAGE
• > End of message

Enable/Disable parts of code

main.cpp

#define OLED_ENABLED true # Enable/Disable OLED screen
#define CAN_ENABLED true  # Enable/Disable CAN (loop() doesn't run)
#define SCOM_ENABLED true # Enable/Disable Commands via Serial 

3. Sources

Wouldn't have done anything without:

• https://github.com/the6p4c/Flatpack2
• https://github.com/taHC81/Eltek-Flatpack2-ESPhome
• https://openinverter.org/forum/viewtopic.php?t=1351