Why are you still using 8 bit MCUs?

[free_electron]

So you'd need to sell 2000 units before making a profit.

come back when you are doing millions of units. the beancounters will nibble you to death.

[ddavidebor]

Why 8 bit?

I'm asking myself why i can't find 4 bit mcu ;-)

[free_electron]

Why 8 bit?

I'm asking myself why i can't find 4 bit mcu ;-)

4bit is for wimps.

1 bit is the clear winner ! MC14500

http://en.wikipedia.org/wiki/Motorola_MC14500B

[c4757p]

4bit is for wimps.

1 bit is the clear winner ! MC14500

http://en.wikipedia.org/wiki/Motorola_MC14500B

Aren't there easier ways to commit suicide?

[westfw]

easier ways to commit suicide?

Hardwired ECL logic.

[c4757p]

No, easier, not just more reliable.

[Harvs]

Why 8 bit?

I'm asking myself why i can't find 4 bit mcu ;-)

4bit is for wimps.

1 bit is the clear winner ! MC14500

http://en.wikipedia.org/wiki/Motorola_MC14500B

Wow, I just had a look at that.  The guy who wrote that has got a VHDL model for it.  It's one clocked process that spans roughly one page!

[Kjelt]

Hehehe seven years ago i contacted a chinese 4 bit microcontroller salesperson who offered micros for less then 6 cents. My projectleader was interested so i investigated. The reason they were so cheap was that they were designed for toys and this was the fifth baddest selection of the product , there were in the final test more then 30 of the 128 bytes  of RAM corrupt, but on each device different ofcourse. On my question how you can work with that the manufacturer said to write test code in beginning of progam to test which cells were bad I told my projectleader then to go and @&€&@€& and do it himself but he already got the point.

[AndyC_772]

The point about cost is a very valid one, though. If a 6 cent processor can be made to work, and all it needs to do is make a toy go 'pow' or 'zap' depending on which button is pressed, then it's really not a bad solution. If the nearest PIC that could do the job is, say, 60 cents, then it's immediately priced itself out of the market.

On several occasions I've found myself needing to design a processor into an extremely low cost product, and I've struggled to find parts much below, say, $0.50 even in decent volume. I know there are plenty of Far Eastern manufacturers of cheap microcontrollers, but they have no presence in Western markets - no distributors, no technical support, and in some cases, no English data sheets.

Has anyone ever been called upon to design a toy, or a TV remote, or some other similar device that will sell in vast numbers but has a parts budget <$1? How did you go about it? Whose parts did you use?

[Abstr7ct]

Maybe irrelevant, but in my area where there is no distributor of 8-bit MCUs, I find a PIC18FXXX MCU costs as high as 30$.

[WarSim]

PIC24F, PIC24E, dsPICF

They are essentially the same.

Yup, they are just different speeds and RAM really,  I still picked three chips one from each to have on hand. 

[WarSim]

The point about cost is a very valid one, though. If a 6 cent processor can be made to work, and all it needs to do is make a toy go 'pow' or 'zap' depending on which button is pressed, then it's really not a bad solution. If the nearest PIC that could do the job is, say, 60 cents, then it's immediately priced itself out of the market.

On several occasions I've found myself needing to design a processor into an extremely low cost product, and I've struggled to find parts much below, say, $0.50 even in decent volume. I know there are plenty of Far Eastern manufacturers of cheap microcontrollers, but they have no presence in Western markets - no distributors, no technical support, and in some cases, no English data sheets.

Has anyone ever been called upon to design a toy, or a TV remote, or some other similar device that will sell in vast numbers but has a parts budget <$1? How did you go about it? Whose parts did you use?

The PIC10F220 can be had for 0.14 in moderate lots.  who knows how cheep they get in huge lots. 

[dannyf]

some other similar device that will sell in vast numbers but has a parts budget <$1?

In some parts of the world, there numerous mcus (some brand names) that sell for less than $0.16 each.

[nctnico]

Has anyone ever been called upon to design a toy, or a TV remote, or some other similar device that will sell in vast numbers but has a parts budget <$1? How did you go about it? Whose parts did you use?

A couple of months ago I co-designed a device which falls in that category. We used an MSP430. It needed the least external components and had the lowest power consumption so the battery could be much smaller (and cheaper).

[amyk]

Hehehe seven years ago i contacted a chinese 4 bit microcontroller salesperson who offered micros for less then 6 cents. My projectleader was interested so i investigated. The reason they were so cheap was that they were designed for toys and this was the fifth baddest selection of the product , there were in the final test more then 30 of the 128 bytes  of RAM corrupt, but on each device different ofcourse. On my question how you can work with that the manufacturer said to write test code in beginning of progam to test which cells were bad I told my projectleader then to go and @&€&@€& and do it himself but he already got the point.

This is actually quite common at the ultra-low-end: devices that are not 100% functional, but where the intent is that you don't actually use 100% of the functionality in your product. I've seen a design where a particular output could be jumpered using solder pads to one of several I/O pins - the firmware is written to set all of them to the same value, but the MCU is imperfect and so on assembly/test they choose a pin which works. It makes sense to the MCU company as they can make saleable product out of die which would otherwise be scrapped.

Microchip does this "sell as-is" with their PICs in China; look up CF745 and CF775 if you want more info.

[AndyC_772]

some other similar device that will sell in vast numbers but has a parts budget <$1?

In some parts of the world, there numerous mcus (some brand names) that sell for less than $0.16 each.

This is exactly what I'm getting at - but can you name any specific examples who will provide developer support and tools in the UK?

It's OK to forgo some of the nice features that might be expected in 'mainstream', western market products. It's OK to for the part to be OTP rather than Flash based, for example. I can probably do without debug features, provided there's a reprogrammable version of the device I can prototype with. Heck, if they're cheap enough, I can buy a hundred of them and a ZIF socket.

I've seen plenty of parts that aren't marked with any kind of manufacturer's logo - that's fine - and I know they're often available untested. Even that may even be OK; provided most of them work, the odd unit off the line which doesn't go 'zap' or 'pow' when prodded can be reworked.

[Rufus]

for less then 6 cents. My projectleader was interested so i investigated. The reason they were so cheap was that they were designed for toys and this was the fifth baddest selection of the product , there were in the final test more then 30 of the 128 bytes  of RAM corrupt, but on each device different ofcourse. On my question how you can work with that the manufacturer said to write test code in beginning of progam to test which cells were bad I told my projectleader then to go and @&€&@€& and do it himself but he already got the point.

And if parts with all the RAM good cost $0.16 and you are going to buy a million you have a $100,000 budget to write that test code. Doesn't sound like whatever point was given and got was the right one.

[nctnico]

I've seen plenty of parts that aren't marked with any kind of manufacturer's logo - that's fine - and I know they're often available untested. Even that may even be OK; provided most of them work, the odd unit off the line which doesn't go 'zap' or 'pow' when prodded can be reworked.

The interesting question here is whether you can test chips cheaper than the manufacturer can. And even then chances are you end up with devices which failed testing so many of them may be useless. So if you go down that road you probably need to make sure the supplier can guarantee a certain percentage of working devices.

[dannyf]

who will provide developer support and tools in the UK?

No idea about the UK. Taiwanese companies are very aggressive at the low-end of the market (toys, washers / dryers, etc.). Some of their high-end vendors (relatively speaking), like Holtek, do provide tools. Haier (a Chinese company) provides tools if you contact them. Some start-ups, like LogicGreen, provide samples / tools upon request.

ST also markets their STM8 chips very aggressively so that's another possibility.

[AndyC_772]

The interesting question here is whether you can test chips cheaper than the manufacturer can. And even then chances are you end up with devices which failed testing so many of them may be useless. So if you go down that road you probably need to make sure the supplier can guarantee a certain percentage of working devices.

Agreed, although there's also the important question over what constitutes a test pass vs fail.

The manufacturer must fail a chip if any feature doesn't work as per the data sheet spec, but in a given application that may be unnecessarily harsh. Perhaps I don't care if a couple of the ADC channels don't work, because I'm not using them anyway. Maybe the pin I'm using as a switch input doesn't actually work as an output, but again, not a problem in my circuit. The manufacturer's yield might be, say, 70% of parts meeting the spec in its entirety, but as far as my product is concerned, 98% of them might be usable.

Don't get me wrong, I don't like the idea of making any product with defective components, but I can see the economic argument for it right at the bottom end. If the end product has to be tested anyway, and especially if a handful of customer returns can be tolerated, then maybe there's no need to test the chip itself at all as a separate step - just replace it if the product coming off the line doesn't work.

No idea about the UK. Taiwanese companies are very aggressive at the low-end of the market (toys, washers / dryers, etc.). Some of their high-end vendors (relatively speaking), like Holtek, do provide tools. Haier (a Chinese company) provides tools if you contact them. Some start-ups, like LogicGreen, provide samples / tools upon request.

ST also markets their STM8 chips very aggressively so that's another possibility.

Thanks for the suggestions - I might start with ST and go from there.

[SeanB]

Intel does that with Pentiums and Celerons, the ones with cache bit errors are masked out to remove the half of the cache that is bad and sold cheaply. Same with clock speed, they are binned into speed grades and sold as such.

[AndyC_772]

Well, yes, but that's not quite the same thing from the end customer's perspective. What they're selling is a fully tested, guaranteed part which happens to have lesser (but known) specification, not an example of the 'full' device which may or may not work.

[Kjelt]

And if parts with all the RAM good cost $0.16 and you are going to buy a million you have a $100,000 budget to write that test code. Doesn't sound like whatever point was given and got was the right one.

The biggest issue was probably the unknown factor with these chips, is the defective areas a onetime issue at production or an ongoing one with a bad process and parts of the uC failing in the near future. I work for a company that literally guarantees some products for 60000 + hours at temperatures of 90 C. We buy elco.s that cost a multiple of this to guarantee that lifetime. But then the specs of these components are guaranteed by he supplier. Needless to say that the chinese manufacturer had little guarantees to give 

[WarSim]

And if parts with all the RAM good cost $0.16 and you are going to buy a million you have a $100,000 budget to write that test code. Doesn't sound like whatever point was given and got was the right one.

The biggest issue was probably the unknown factor with these chips, is the defective areas a onetime issue at production or an ongoing one with a bad process and parts of the uC failing in the near future. I work for a company that literally guarantees some products for 60000 + hours at temperatures of 90 C. We buy elco.s that cost a multiple of this to guarantee that lifetime. But then the specs of these components are guaranteed by he supplier. Needless to say that the chinese manufacturer had little guarantees to give 

Same with all industries.  I have used a $600.00 5/16 2.5" steal bolt before because lives depended on it.  If you need assurances then it costs.  If you don't need assurances you can save money. 

Take the toy idea.  A kid left a top at work.  It had 4 lights that flashed for a persistence of vision effect.  It had 6 LEDs, passives, a switch, a bare uC and a battery.  The uC would PWM the LEDs for different patterns.  Apparently new only 4 LEDs ever lit up and before the battery died another died.  This toy was still sold and played with by a child and adults after being abandoned at work.  This is the type of product that receives these cheep uCs.  Build it, if more than half of the lights work full price.  if less discount for dollar stores.  If all light up then mark it up as a rare collectors item.  It would be silly to put a 50 cent verified chip in a 99 cent toy.  It would take away the profit. 

[cloudscapes]

Lets say I only need to read a pot and control some LEDs and/or a relay.

Cheapest PIC32 right now on mouser, 100 lot. $1.73
Cheapest AVR right now on mouser, 100 lot. $0.576

That's $120 in your pocket if you choose to go the smart route. Also, more PCB space.

I can't believe this thread even made it past 2 pages.