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Comment by gmiller123456 | Hacker News Reader

So, it looks like you program the RA4M1, and the ESP32 is just there for wifi (and USB interface). That seems like an incredibly odd and wasteful choice. I didn't see any explanation as to why they did it that way.

I was kinda worried the interface to the ESP32 would have been like the origional ESP8266 where you used AT commands. But it looks like the Wifi library abstracts out whatever interface they're using for the ESP32, so I was at least happy to see that.

Since the ESP32 handles the USB interface, it's probably possible to program both microcontrollers. I can't imagine a practical use for that, but bet it gets done pretty quick.

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Pretty standard to use ATWINC1500, CYW43439, ESP8266, or ESP32 to add Wifi over UART/SPI/i2c to another microcontrol chip.

This is done with the RP Pico W, Adafruit Feather M0 Wifi / or Airlift, 3d Printer boards (Duet Wifi) and allows you to add Wifi to code bases already written for these boards without worrying about rewriting and/or hitting memory performance issues with running Wifi and logic on a single chip.

Not to mention having your interface chip not be what you're organizing increases reliably and prevents bricking

5V GPIO is something the Uno line has historically had since the very beginning (and an assumption of having it is baked into thousands of getting started with Arduino books and guides) and I suspect using the RA4M1 is to help keep this capability.

Wouldn't a bunch of logic level converters resolve that?

It could but it's more cost and complexity.

Logic level converters are HARD. You basically need to rebuild internal structure of GPIO external to the MCU. It needs to support high speed, high current, input or output, open-drain/open-collector, customizable resistor pull-up/down.... All external to the MCU.

Arduino on ESP32 isn't the best. It works, but it has a bunch of missing features and sometimes acts oddly in the arduino ecosystem.

I imagine they used the Ra4M1 for stability concerns.

This is just baseless and I don't even understand to what end. ESP32 isn't missing features vs say Arduino Uno and does not act oddly.

Agreed. I've had one running for 3 years as a garage door opener relay and it works like a charm. Reboots after power failures everytime.

I think you missed the intent of the message you’re replying to. They are saying that when you use the Arduino ecosystem on the ESP32 you are missing features (whether that’s Arduino features that don’t work on the ESP32 or more likely ESP32 features that are not available through the Arduino toolchain).

Personally for the latter reason I think if you’re targeting the ESP32 you should skip the Arduino ecosystem and just write native code.

Espressif publishes their own C SDK for their ESP32 products. They also support Rust development (using the mainline compiler) on some of the RISC-V modules like the ESP32-C3.

Arduino libraries don't all work on the ESP32, and some respond oddly vs an ATMEGA chip. Arduino framework on the ESP32 is an afterthought, it wasn't designed for it.

I use the ESP IDF framework because it has so much better support.

The biggest downside of the ESP32 is that it doesn't support 5V GPIO, and I believe having to run the wifi stack makes running cycle-accurate code quite tricky.

I have had great luck running ESP32 apps with the Arduino framework. Everything I have tried works. Admittedly I am only using GPIO, SPI bus displays, I2C sensors and displays, WIFI web servers serving REACT apps, WIFI posting to other web services, and ESP-NOW layer 2 direct WIFI connectivity. But this stuff has been flawless.

p.s. the ESP32 dev modules suck and brownout randomly with WIFI usage. I use my own PCB and put fat tantalum caps feeding the modules.

Ya, there's a huge discrepancy of quality in their modules.

Some module LDOs cap out at 500mA, but you need 800mA and proper bypass caps on the VDD for WiFi spikes. Good call on the Tantalum caps.

Back in 2010 when I was into Arduino I made a GPS/GSM Car Tracker with my Arduino Mega (ATMega 1280, an 8-Bit 16MHz MCU).

I did that by speaking AT serial to a Telit GM862-GPS module. I can’t find the actual CPU spec now but it contained a much more powerful CPU, I recall it being ARM but can’t find evidence of that now :) it also had a python interpreter.

Same energy.

https://www.sparkfun.com/products/retired/7917

The USB interface can be routed to either the RA4M1 or the ESP32, actually. I expect most people will essentially just use the ESP32 as a wifi modem.

A big reason to do this is that RF is hard. You really don't want to design a custom wifi board if you can at all avoid it, and using a pre-certified module for it greatly reduces complexity. Not to mention that very few wifi-capable chips support 5V gpio.

>So, it looks like you program the RA4M1, and the ESP32 is just there for wifi (and USB interface). That seems like an incredibly odd and wasteful choice.

They don't want to be responsible for security?

I've done this to airgap devices.

What's the benefit of this RA4M1 processor over something like an Arm cortex ? I see the only thing that sticks out to me is the 24 volt tolerance?

The RA4M1 is an ARM Cortex M4 SoC.

The RA4M1 is an ARM Cortex core, but it could be that Renesas offered to subsidize some of the cost of the board by providing the chips with some kind of sweetheart deal. Not a bad idea if so, Renesas can generate a whole lot of interest in their platform for what is probably a rounding error in their bottom line. And they've previously invested in Arduino (https://www.eenewseurope.com/en/renesas-backs-arduino-with-1...).

Yeah that was my thought. Renesas Isn't a big player in the uc market at all. I don't think I've ever heard of anyone using their parts.

i have used renesas microcontrollers in probably 20 defense contracts fwiw

How open is the toolchain/SDK for Renesas parts? I.e. can they be used with gcc/gdb/(c)make with reasonably low effort (like esp32, stm32, rp2040) or is the only realistic option using their IDE?

it's all open source, you can see part of it here https://github.com/arduino/ArduinoCore-renesas

you can use GCC with https://github.com/renesas/fsp if you want to go very low level.

their official fat sdk is a run of the mill eclipse reskin w the usual gcc ports and half working libc options last i used it :-)

What defense area? I've done a ton of random aerospace stuff and usually end up using STM or NXP. All the critical systems have been some horrifying PPC or Sparc derivative.

Renesas is (or was, at least) pretty big in the automotive sector. They are much less common in general consumer electronics, though.

They're a big deal in industrial/automotive/defense but they don't have a ton of visibility. Perhaps why they'd be interested in more outreach, Atmel and others like STMicro definitely reaped benefits from engaging with hobby/educational users at probably negligible cost. Arduino has also been trying to position themselves as a legitimate friendly platform for industrial automation, so it could be a good match.

Back in the day, before being spun off from Hitachi, Renesas made the CPU for the original Lego Mindstorms: https://en.wikipedia.org/wiki/H8_Family

Personally I'm really stoked about the Uno finally getting a 32 bit ARM core. And an M4 at that! I would've thought maybe a M0+ (like the RP Pico) on the Uno and perhaps an M4 on a hypothetical future Mega update.

Good stuff from Arduino. The AVR on the previous Uno revs was getting quite outdated. Simple to use yes, but the Arduino environment mostly abstracts over that and only "power users" ever need to dive into peripheral registers and whatnot (eg to use interrupts).

What's the difference between an Arduino arm cortex and just getting an adafruit feather board? They have m4's on them and can be programmed with an Arduino IDE and the same tools.

Not much difference, it's just good to see Arduino coming back as decent competition.

Well, this M4 is most likely much slower than Rp2040 (2.5x difference in clock speed plus dual core). At the same clock the difference between M0+ and M4 isn't too dramatic (unless you use FPU).

I see no reason for them not to go with the RA4M2 version (with 100mhz clock and more memory). The RA4M1 Only has 32KB of memory, and slow clock. Arm M4 is a superset of M0, so clock for clock M4 should be faster. Given the price point for this board compared to the RP2040, I see no reason to give it such a limited processor.

does this mean you can use ESPhome on the Uno R4?

rip lipo packs

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