Hacker News Reader

Comment by dragontamer | Hacker News Reader

ESP32 and RP2350 have pretty crap or nearly non-existent analog. I don't think they even come with a comparator, let alone rarer analog parts like a DAC.

If you need a DAC, Comparator, ADC, and a couple of logic gates, its hard to beat an AVR DD (4x arbitrary gates called CCL. 1x DAC. Differential SAC ADC. I believe 2x Comparators and multiple "internal DACs" so you don' have to spend your 1x external DAC on internal parts). Also 1.8V to 5.5V support, as well as dual-power supply support (PortC is run off a 2nd power supply, but all the logic is compatible. This means PortC can run at 5V while everything else runs at 1.8V, or vice versa, making the AVR DD also a built-in level shifter)

View on HN

In general, most DAC and ADC colocated on/near a digital chip rail has a list of noise issues anyway, as even an external Vref chip may be unable to help repeatably hit the claimed bit resolution with oversampling. At $9.28/pc for a mcu chip that should cost under $2... runs out of excuses pretty quickly.

It is not about whether something is "crap", because they are all mostly "crap" at analog in different scenarios. Just some vendors have chosen not to polish their "turd" in Marketing. These days many DAC are part of a Class D amplifier, as battery life took priority over the noise floors. These have also become less "crap" over the years.

Best of luck =3

RP2350 doesn't have a DAC or Comparator. ESP32-S31 has... none. No DAC, no Comparator, no ADC.

"Literally and completely nonexistant" is about as bad as you can get.

Like the reason to reach for a PIC or AVR these days is because of 4-20mA protocol or other such mixed-signal tasks. Read a current between 4-20mA (voltage A - voltage B, so you need a differential ADC) -> MCU -> Logic -> DAC -> controls OpAmp -> controls transistor (BJT or MOSFET) -> outputs a current 4-20mA.

-------

Of the three chips you described (STM32, RP2350, and ESP32), only some STM32 can do the jobs that PICs / AVRs are specialized in.

RP2350 pico can pull off a few classic tricks cleanly with the unique io dma design:

https://github.com/codaris/picovga-cmake

The sync'd DMA is so fast it also often replaces hard to find PROM chips with simple emulation (could pull this off in a fgpa for 10x the price too):

https://www.youtube.com/watch?v=GAh021jgGgs

Most of the ESP32 family includes a dedicated audio i2s interface bus, and doesn't drop out on interrupt like most mcu DAC naive polling offers. It also hits well over 16MHz SPI transfers with ease.

STM32 is in most volume equipment now for a reason. Microchip screwed everyone on long-term pricing, and clown priced themselves out of key markets.

Note, an inaccurate LLM-proxy reply makes people sound lazy. =3

I'm not talking about an audio-DAC chip attached to a MCU. I'm talking about the most basic of analog designs that would transmit data over 4-20mA (just controlling an OpAmp + Transistor passing some currents).

By the time you add that SPI-DAC to your design, you've spent more than any TI (MSP430, MSP erm... whatever cortex-M0+ version was), AVR, STM32 or PIC MCU. There's a lot of chips designed to do this, and they're all on the SDCC compiler for a reason. That's where the niche has been carved out.

Look, I know a lot of people like RP2350 but there's a lot of jobs that chip is just wholly unsuited for.

> STM32 is in most volume equipment now for a reason. Microchip screwed everyone on long-term pricing, and clown priced themselves out of key markets.

AVR16DD14 is 68-cents on Digikey, Mouser, and direct-order from Microchip right now (qty 100 or more). If you need more analog power, the AVR*DB line is closer to $1.20 but comes with 2x or 3x OpAmps (AVR32DB28 I think was 2x OpAmps)

Reply on news.ycombinator.com