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1.38 Millimeter Microcontroller

ti.com

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Re: 1.38 Millimeter Microcontroller

#51

Post by Skwid »

arnejenssen wrote: post #17

A silly question (from a non-HW guy). Why are digital bathroom scales so coarse? Some have a weight resolution of +/- 500 grams. Would a better microcontroller make a weight faster or more presise? I guess this TI micro controller is overkill for a bathroom scale.

As others have said, the crap resolution is to mask the crap repeatability. Better processing can help, but good enough processing fits in the cheapest of microcontrollers. ADC quality is more important, signal conditioning and sensor quality more important still. The biggest factor for accuracy is likely calibration though. A sensor that's 2% accurate with a 2 point calibration can easily become a 0.25% sensor with a 5 point, 3 temperature calibration. But that all takes time, and unless you're running huge batches it adds too much to the bottom line of a low cost product. Source: Designed strain gauge sensors and manufacturing processes for a living

Re: 1.38 Millimeter Microcontroller

#53

Post by Karliss »

anonli wrote: post #34

At $0.20 in 1k quantities, this is TI's answer to the CH32V003, Puya PY32, and the STM32C0 series. It's great to see tier-1 silicon vendors participating in the race to the bottom for jellybean microcontrollers. The 1KB of SRAM is admittedly very tight (even WCH's 10-cent RISC-V parts usually give you 2KB), so you are strictly in bare-metal, carefully-managing-your-stack territory.

1KB isn't so bad unless you are making something complicated or need large buffers. You can do quite a bit of nontrivial stuff with it. Years ago I made universal remote with ATtiny13 + external EEPROM for storing remote data. It has only 64 bytes of RAM, that's what I would call very tight. Was still able to program it in C, 1KB flash and number of pins were bigger limiting factor than ram.

Plenty of DIY projects used ATtiny2313 with V-USB. That's a pure software USB implementation bit banging the IO pins (not a USB stack on top of hardware USB support)+ your application logic squeezed into 2K of flash + 128 bytes of ram.

Chips like this are great for digital glue logic. Read a sensor, read a button press, blink some LEDs with simple state machine or control loop.

Re: 1.38 Millimeter Microcontroller

#54

Post by 7734128 »

zipy124 wrote: post #47
7734128 wrote: post #28

Does anyone know what would the price of this be, roughly of course, given that a customer ordered some thousands or tens of thousands? I have no grasp of even the magnitude of the price for something like this.

Price is listed on the site, the most expensive version is: 1-99 $0.720 100-249 $0.48925 0-999 $0.378 1,000+ $0.251

Oh, I'm an idiot who didn't see that at all. Thanks.

Re: 1.38 Millimeter Microcontroller

#55

Post by analog31 »

self_awareness wrote: post #2

It seems awesome, but I'm having a problem with figuring out how can a "normal" person use it. How would YOU use it, reader of this comment?

Consumer electronics can be designed to extremely tight budgets for cost and power consumption. Designers will choose a chip based on a chip having precisely the features needed, zero current wasted on features they don't need, and seemingly tiny price differences.

Re: 1.38 Millimeter Microcontroller

#56

Post by Scene_Cast2 »

arnejenssen wrote: post #17

A silly question (from a non-HW guy). Why are digital bathroom scales so coarse? Some have a weight resolution of +/- 500 grams. Would a better microcontroller make a weight faster or more presise? I guess this TI micro controller is overkill for a bathroom scale.

I've spent the last several years of building a very, very fancy scale (well, more of an industrial and R&D lab tool that can be used as a scale).

The reason is that most people use a dirt cheap HX711 or cheaper. A fancier microcontroller doesn't help all that much.

I got to 100dB of dynamic range at 1ksps (1 gram of noise at 100kg max load), so it's very much doable.

Re: 1.38 Millimeter Microcontroller

#57

Post by LeifCarrotson »

Karliss wrote: post #53
anonli wrote: post #34

At $0.20 in 1k quantities, this is TI's answer to the CH32V003, Puya PY32, and the STM32C0 series. It's great to see tier-1 silicon vendors participating in the race to the bottom for jellybean microcontrollers. The 1KB of SRAM is admittedly very tight (even WCH's 10-cent RISC-V parts usually give you 2KB), so you are strictly in bare-metal, carefully-managing-your-stack territory.

1KB isn't so bad unless you are making something complicated or need large buffers. You can do quite a bit of nontrivial stuff with it. Years ago I made universal remote with ATtiny13 + external EEPROM for storing remote data. It has only 64 bytes of RAM, that's what I would call very tight. Was still able to program it in C, 1KB flash and number of pins were bigger limiting factor than ram. Plenty of DIY projects us…

Yes, that's "bare metal" as opposed to programming in MicroPython, Javascript with Espruino, Lua/NodeMCU, Rust, or adding your C application on top of an off-the-shelf RTOS.

C support is basically universal these days, very few chips require you to program in only assembly anymore.

Re: 1.38 Millimeter Microcontroller

#58

Post by daveguy »

LeifCarrotson wrote: post #57
Karliss wrote: post #53

Earlier quoted context omitted.

1KB isn't so bad unless you are making something complicated or need large buffers. You can do quite a bit of nontrivial stuff with it. Years ago I made universal remote with ATtiny13 + external EEPROM for storing remote data. It has only 64 bytes of RAM, that's what I would call very tight. Was still able to program it in C, 1KB flash and number of pins were bigger limiting factor than ram. Plenty of DIY projects us…

Yes, that's "bare metal" as opposed to programming in MicroPython, Javascript with Espruino, Lua/NodeMCU, Rust, or adding your C application on top of an off-the-shelf RTOS. C support is basically universal these days, very few chips require you to program in only assembly anymore.

Rust compiles to bare metal (assembly aka machine instruction code), just like C does.

Re: 1.38 Millimeter Microcontroller

#59

Post by GordonS »

emctech wrote: post #45
tauntz wrote: post #41

Earlier quoted context omitted.

These earrings look awesome btw!

Thank you! I want to try and sell them but I just have a few bugs to squash and to finish off the mechanical design of the charging cradle.

Have you blogged about the earrings perchance? They really do look great, and I'd love to see some details of your process.

Re: 1.38 Millimeter Microcontroller

#60

Post by LeifCarrotson »

numpad0 wrote: post #39
arnejenssen wrote: post #17

A silly question (from a non-HW guy). Why are digital bathroom scales so coarse? Some have a weight resolution of +/- 500 grams. Would a better microcontroller make a weight faster or more presise? I guess this TI micro controller is overkill for a bathroom scale.

Digital scales generally work by warping metal pieces and forcing a flex film resistor glued on the piece to be stretched along, causing its resistance to change, thereby breaking the balance of a Wheatstone bridge, creating force-proportional current to occur, which is finally read out with an ADC. I guess the overall finickiness of that can't be instantly improved by a better microcontroller alone? They drift and h…

You've described a load cell, which is commonly used in laboratory and industrial environments to resolutions exceeding 0.05% of full scale. I've used these in the past with great success:

https://www.interfaceforce.com/products/load-cells/low-profi...

Click the "Specifications" tab to see the various error sources. Interface's technical library (linked at the top right of their shop) is a great training tool too, if you want to learn more. To keep your NIST certification - and to maintain accuracy after a high-stress...incident... you need to do occasional recalibration. That would be a problem for a consumer product, but with good mounting and overload protection they really don't change that much over time.

Then you've got the electronics, and the amplifier required to get the rated precision out of that load cell costs more than the load cell itself.

Achieving those performance targets costs money, and people buy the cheapest scale that says "Accurate High Precision Digital Bathroom Scale Glass" on the Amazon listing.

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