Cheap chip

Hello,

For a small project, which should be very cost oriented, I need a simple microcontroller whos main task should be implementing SMI serial interface. This means it should heve at least 2 I/O pins which are TRI-STATE enabled. It should have a very small on-chip RAM for data and small on-chip memory (can be even OTP) for the code.

I would also want it to have a nice development environment (actualy, ANSI-C compiler should be ok).

Do you know of a good enough microcontroller (its cost and how do I get it)? Do you think I should go for those 8-bit ones for their simplicity (cheap chip but expensive tools) or for the 8051-compatible for their well spread and tools support?

Reply to
Nadav
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Do you mean SMB / i2c BUS / two wire SCL/SDA protocol ? Do you need master, or slave - what Speed ?

There is no 'or'...

Look at P87LPC760, for i2c in hardware, OTP. Look at C8051F305 for FLASH, 99c/10K, on chip debug. SMbus in HW Look at P89LPCxxx families, in 8/14/20 pins, but the smallest ones lack Hardware i2c support.

-jg

Reply to
Jim Granville

Thanks Jim,

SMI (serial management interface) is a two wire protocol specify up to

2Mhz. I plan to implement it using three of the I/O pins.

You right there is no OR. I meant other not 8051-compatible 8-bit micro. like COP8 and such.

Those part numbers you gave are good leads.

I understand the development tools issue is quite chewed topic on the group, but still, do you have any recommended, cheap tools?

Thanks a lot. Nadav.

Reply to
Nadav

Cygnal would be a good starting point, as ALL their devices have on chip debug, as well as the excellant boolean support of the 8051, and the very fast core. ( you'll need all these :)

The info I found on SMI, says it is a HDLC style Bit-Sync/Bit-stuff/CRC16 at up to 2MBaud, so you might do a master/simple tester in a small uC, but a slave to full spec would need hardware support. Using the SPI hardware on a Cygnal uC might get you close, but it would need some nimble, assembler SW...

-jg

Reply to
Jim Granville

Cygnal (Silicon Labs now) chips are ok, but if the OP is looking for cheap chips, go elsewhere. I find their prices to be the highest for

8051 type devices, or for any other comparible devices for that matter, that I can find.

I think the MSP430 is a very nice family and has some cheap tools as well for small projects.

The PICs are ok, a lot of people use them, but they are a limited architecture if that matters to you. Maybe limited is not the right term, but many consider the instruction set "kludgy". Others say it doesn't matter, you can still get a lot done.

--
Rick "rickman" Collins

rick.collins@XYarius.com
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Reply to
rickman

Web prices (Mouser) TI 430F1121A 256RAM, 2KW Vanilla ADC, no MUL, 8MHz, no SPI ? Price $4.79 1+ to $4.07/250+

Cygnal C8051F305 256RAM, 2KB Full ADC, PCA, MUL, 25MHz Price $4.45 1+ to $2.13/250+

C8051F330, which has way more resource than F1121A, is $3.78/250+ [8KF,768R, ADC/DAC/PCA, SPI/i2c/UART 5V compatible IO, 2% Osc, LVD ...]

This F330 comes in DIP20 as well, for vero-projects.

If the OP wants a full spec slave (2Mhz BitSync), ANY small uC will struggle, but the clock speed will be very important, and SPI HW is likely to be important. My advice would be to start development on the C8051F330, and when the SW is done, scan smaller devices like P89LPC914 etc

-jg

Reply to
Jim Granville

"Nadav" skrev i meddelandet news: snipped-for-privacy@posting.google.com...

After looking at the SMI specification, I think you have two alternatives.

1) Connect the controller to a simple GAL circuit. 2) Use a pretty fast micro. You probably need > 20 MIPS - Maybe up to 40... You may be able to use an SPI interface, but this have to use open collector driving Either tristate or zero On reception, you need to look at the edge of the clock, so that you can disable the transmitter. Maybe a 24 MHz AVR (The new ATmega48) can do this, but this is a 5 Volt chip and I suspect you want a 3 volt chip. The AT94S05 FPSLIC which combines an AVR and a small (5 kgates) FPGA will do this easily.
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Best Regards,
Ulf Samuelsson   ulf@a-t-m-e-l.com
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Reply to
Ulf Samuelsson

Thanks a lolt guys!

Grate Grate advaises!

I guess I've got what I needed to start.

Reply to
Nadav

This part comes in an 11 pin package with only 8 IO pins! The F1121 has

14 IOs pins and separate pins for the xtal connections. Hardly comparable.

Or maybe you need to find a vendor with better prices...

Digikey

Digi-Key Part Number 296-12703-5-ND Manufacturer Part Number MSP430F1121AIDGV Description IC 16BIT MCU 4KB FLASH 20-TVSOP Quantity Available 1945 Price Break

1 3.830 25 3.060 100 2.380 250 2.261 500 2.210 All prices are in US dollars.

Last time I checked, 2.26 was a lot cheaper than 3.78, about 2/3 the price, no?

But to be honest, I have a bit of a bias based on the pricing I have seen in the past on Cygnal (Silabs) products. The numbers you posted are much better than the Digikey numbers for the same Cygnal parts. In the future, I will look a bit harder at Cygnal parts. But even Cygnal's own prices are not all that good. They used to sold directly exclusively. I guess they had not penetrated distribution at that point.

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Rick "rickman" Collins

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Reply to
rickman

I think you mean DISTRIBUTOR ? The IC vendors prices tend to be more sensible/consistant, if you can get to them..

This does illustrate very well some of the plain silly price curves that are out there.

I have made the point to IC manufacturers before that a key reason to publish 1K/10K prices ( as many (most?) now do) is to give designers a sensible reference point. One-off prices really do not matter, but the WEB now allows designers to quickly compare apples and oranges and prices are used as part of any design decision.

Doesn't make sense to have some old, or distorted price node influence a design decision, but that's what happens regularly without vendor Qty prices. Cygnal used to list their 10K prices, but SiliconLabs removed that. Not a clever move.

-jg

Reply to
Jim Granville

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