{"id":11168,"date":"2026-02-15T23:21:50","date_gmt":"2026-02-15T23:21:50","guid":{"rendered":"https:\/\/purplemeanie.co.uk\/?p=11168"},"modified":"2026-02-15T23:34:45","modified_gmt":"2026-02-15T23:34:45","slug":"esp32ret-on-an-adafruit-esp32-s3-tft","status":"publish","type":"post","link":"https:\/\/purplemeanie.co.uk\/index.php\/2026\/02\/15\/esp32ret-on-an-adafruit-esp32-s3-tft\/","title":{"rendered":"ESP32RET on an Adafruit ESP32-S3 TFT"},"content":{"rendered":"\n

Well, this was another one of those rabbit hole projects. I’d got myself a home grown CANbus sniffer that talked in the Lawicel format to SavvyCan and allowed me to sniff CANbus data<\/a> reasonably reliably.\u00a0<\/p>\n\n\n\n

BUT, I had to be connected to the sniffer over a serial interface and that was becoming a problem in my crowded office\/lab environment. My current sniffer was also running out of steam (there’s a mental image) and so I needed more grunt too.<\/p>\n\n\n\n

I also want my Sniffers to have a locally attached display on them… it’s good to be able to see how many packets are flowing and to be able to have a semi-intelligent sniffer showing other things locally without having to have a PC connected to them. An attached display is also great for some quick diagnostics when things aren’t going the way you thought they would.<\/p>\n\n\n\n

So I decided to see if I could get the ESP32RET project (wifi streaming of CAN frames over WiFi) running on an Adafruit ESP32-S3 TFT board… what could possibly go wrong!<\/p>\n\n\n\n

And before we get too far into this… here’s the GitHub repo for anyone who doesn’t want to read any further… don’t blame you TBH!<\/p>\n\n\n\n

https:\/\/github.com\/Purplemeanie\/ESP32RET.git<\/a><\/p>\n\n\n\n

The OG CANBus Sniffer<\/h2>\n\n\n\n

But before we get into the ESP32RET project… here’s what I’d done already. A couple of CANBus projects, one a packet generator and one a sniffer. Both based around the Adafruit RP2040 CAN Feather – I really like these boards!<\/p>\n

I worked for a few months with these devices sniffing the various CANBuses I was playing with.<\/p>\n

The Sniffer gets connected to a PC (Mac) and was controlled by the SavvyCan<\/a> software using a Lawicel\/SLCAN protocol. All was fine, but it did need a serial connection and topped out at about 800 packets\/sec.<\/p>\n

Here’s the two projects connected together, being tested back to back.<\/p>\n\n\n\n

\"\"
RP2040 Sniffer and Generator<\/figcaption><\/figure>\n\n\n\n

As you can see the displays are really useful.<\/p>\n\n\n\n

The generator also had a “command over serial” interface. So, via the serial interface to my Mac, I could turn on and off any of 4 different frame generation patterns, with data length, data content (fixed, count, random) and frequency all configurable. It’s been really useful at loading up a bus to see what breaks.<\/p>\n\n\n\n

The sniffer was also really useful, getting me through the early stages of my test bench setup… setting up the VCU, PDM, DCDC and BMS (if you know you know).<\/p>\n\n\n\n

Anyway back to the main topic… ESP32RET on ESP32-S3.<\/p>\n\n\n\n

Why ESPRET on ESP32-S3<\/h3>\n\n\n\n

… because I over-engineer stuff… that should be obvious by now.<\/p>\n\n\n\n

I’d seen the ESP32RET project being used by other automotive peeps and it looked cool, but I had my RP2040 based boards and that was enough to be going on with.<\/p>\n\n\n\n

But, with the Lawicel ascii CAN-frame over serial protocol that SavvyCan uses and fact that my boards needed to be tethered to a serial port, these things started to become problems.<\/p>\n\n\n\n

My Brusa DCDC converter generates over 600 CAN packets a second just doing nothing, and I was only getting about 800 frames\/sec between my Generator and Sniffer. So that could be a bottle neck.<\/p>\n\n\n\n

And… I was having to drape a 3m USB3 cable across my office so I could connect my desktop Mac to my Sniffer boards. That wasn’t ideal.<\/p>\n\n\n\n

So I thought I’d have a look at getting the ESP32RET project running.<\/p>\n\n\n\n

ESP32RET<\/h3>\n\n\n\n

This is a very cool project, here:\u00a0https:\/\/github.com\/collin80\/ESP32RET.git<\/a><\/p>\n\n\n\n

It runs on an ESP32 (so already pretty powerful) and can do a bunch of stuff, including:<\/p>\n\n\n\n