8051 or HC(S)08 ??

[eos33]

hi all,

i am a beginner into the MCU.

as i know,there are many kinds of the MCU in the embedded control.

currently i have two choices of MCU,the one is enhanced 8051 compatible mcu and the other one is the HCS08 mcu.

have anyone had used both of these and simply list the advantage and disadvantage between these two type MCU?

they both have many extra functions..like ADC,KBI,UART,TIMER...etc.

thank you for your valuable suggestion and it will be helpful for me to make the decision.

[Pingu]

As a beginner you'll benefit from the BDM that the HCS08 and new RS08 have. Makes programming and debugging much easier and as you spend more time debugging than writting code that's the feature I love!

Pingu

[rocco]

Hi, eos:

I've programmed the 8051 since the early '80s, and still have to maintain some 8051 code. I've never liked it. It is a difficult architecture to work with, but that can be explained by the fact that it was designed back in the '70s.

It's still popular because there is so much legacy code that was written for it.

Here is example code from two different real-life projects. Both snippets read a byte of data from an Analog-to-Digital converter and stores it in memory:

8051:

---

mov R1,#ADC3
movx A,@R1 ;read value from adc after conv.
mov Analog,A

---

HC08:

---

mov ADR,ADCresult ;get ADC result

---

The most annoying 'feature' of the 8051 is the data-pointer (DPTR) register. Since much of the memory addressing take place with the DPTR, it becomes a serious bottleneck when programming. I find that I spend an inordinate number of instructions shuffling addresses in and out of the DPTR.

The instruction set is one of the main reasons I picked the HC08s over the 8051. That, and the fact that it is 25 years younger.