simple question about 8051 Atmel CORE

[nebisman]

Hi friends

Could you tell me how many clock cycles per instruction are for this processor. If it is variable length what is a good average?

:=) thanks ME and gil.

nebisman

 

[gil]

12 as far I know

 

[ME]

The instructions for 8051 cores are variable lenght.
The shortest lenght is 12 clock cycles.
Read this Atmel document:
Architecture Overview www.atmel.com/dyn/resources/prod_documents/DOC0497.PDF

Look at the section about Machine Cycles.


Some instructions like MUL and DIV are 4 * 12 clock cycles.

 

[wzdreamer]

there are some new Atmel's product which has 6 cloks per machine cycle....
but for all other Atmel's devices is 12...
I mean 8051 Architecture....

 

[wzdreamer]

there are some devices which works on 60MHz with internal memory when 12 cloks per cycle....

 

[GeorgeM]

The modern '51 derivatives have 70% of instructions with 1-2 system clocks....

For example, the Cygnal C8051F12x and it can work at 50 MHz and ever at 100 MHz

 

[wzdreamer]

Cygnal 8051 is not Atmel 8051

I can buy AT89S52 for 1.75 USD per 1 pc.
and 18 USD to 34 USD per 1 pc. for Cygnal 8051 family...

choice is yours....

 

[W49N3R]

12 clock cycles to fetch a byte and execute. Instructions that need more than one byte (usualy the ones addressing memory or with included operand values) will require extra one or two memory fetch cycles.

It can leads to 12, 24 or 36 cycles.

Considering yet that the 8051 core uses only one accumulator, some simple task of rotating one bit in a byte in memory uses 3 or more instructions, it can goes to more than 100 clock cycles just to rotate left one bit in some RAM memory byte.


Interesting fact:
I love the 8051, worked with for many years, and still working, but, when you comparing the above 8051 clock cycles to the AVR, this one can rotate one bit in its internal 32 accumulators tied up to the ALU, in a SINGLE clock cycle, that means the AVR does it at least 100 times faster than the plain 8051. In other words, you also could say that if choosing the lower clock frequency for the AVR in order to produce the same results in time than the 8051, the AVR could run in 1/100 clock (for that rotate instruction) and probably in 1/20 of the power consumed by the plain 8051.

One of the AVR tricks is that it fetches memory data in 16 bits wide, so even instructions with 2 bytes are fetched at once, while in the 8051 it takes two machine cycles (24 clock cycles).

Wagner.

 

[GeorgeM]

Interesting fact:
I love the 8051, worked with for many years, and still working, but, when you comparing the above 8051 clock cycles to the AVR, this one can rotate one bit in its internal 32 accumulators tied up to the ALU, in a SINGLE clock cycle, that means the AVR does it at least 100 times faster than the plain 8051.

One of the AVR tricks is that it fetches memory PROGRAM in 16 bits wide, so instruction (2 bytes) are fetched at once, while in the 8051 it takes two machine cycles (24 clock cycles).

To be honest, many 2 bytes instructions of '51 MC are fetched in one machine cycle. Anyway I agree, AVR MC is 20 times really faster the standard 8051 MC and I like the AVR MC & its instruction set (frankly speaking the best choice is the MSP430 instruction set).

The question is what should I do if I need in 50-100 MHz for single instruction. I can buy nine chipest AT89S52 but you know collecting nine pregnant women doesn'n give you a child in the month

Regards,
George

 

[gul hameed]

very good discution here
i am happy that boys r involved here in answers

i give u simple answer according to my knowlwdge
external crystal is divided by 12 it means if there is 12mhz xtal
then u have 1mega execution cycls and average instructions are takes
2 exe cycles in case of assembly

 

[nachus001]

Hi George M

I think if you need single clock instructions at 50-100 Mhz you should stick to a DSP chip.


Cheers

Nachus

 

[mami_hacky]

A simple way is to use 8051 Core on a FPGA. 8051 or other cores like it are easily obtainable, and I think when implemented on FPGA, it can run for example with a 100 MHz clock frequcny ( normal running freq for a good design in Spartan-II ) additionaly you can implement much more circuit inside FPGA. it is low cost , reliable, easy to develope and ...
OK! using DSPs is really another solution, however, the development time will become larger and ...

 

[GeorgeM]

I think if you need single clock instructions at 50-100 Mhz you should stick to a DSP chip.

Yes, I do. I use the 100 MHz C54xx DSP from TI. But I try to find another way...

A simple way is to use 8051 Core on a FPGA. 8051 or other cores like it are easily obtainable, and I think when implemented on FPGA, it can
run for example with a 100 MHz clock frequcny ( normal running freq for a good design in Spartan-II ) additionaly you can implement much more circuit inside FPGA. it is low cost , reliable, easy to develope and ...

Is there some way to use the AVR core on a FPGA at 50-100 MHz clock?

I am new in FPGA-solutions so one more question. How much does it cost to get the 8051 core on a FPGA?

Regards,
George

 

[ME]

I think if you need single clock instructions at 50-100 Mhz you should stick to a DSP chip.

Yes, I do. I use the 100 MHz C54xx DSP from TI. But I try to find another way...

A simple way is to use 8051 Core on a FPGA. 8051 or other cores like it are easily obtainable, and I think when implemented on FPGA, it can
run for example with a 100 MHz clock frequcny ( normal running freq for a good design in Spartan-II ) additionaly you can implement much more circuit inside FPGA. it is low cost , reliable, easy to develope and ...

Is there some way to use the AVR core on a FPGA at 50-100 MHz clock?

I am new in FPGA-solutions so one more question. How much does it cost to get the 8051 core on a FPGA?

Regards,
George

You can buy AVR ASICs from Atmel running up to 70 MHz.

You can also find some free AVR cores at www.opencores.org