The advantage of the 8051 family is, that you can realize an extremely wide range of applications. So your assembler and compiler tools and the 8051 knowledge can be used most efficient and no need to start with other architectures again from zero.

E.g. for low cost applications the AT89C1051 was intended but the DS80C390 was able to build very complex applications.
Also a wide range of peripherals (ADC, DAC, I2C, CAN, USB) already included in many different 8051 derivates.

And for low cost the AT89C2051 can be used with the analog comparator in combination with an external RC circuit as analog input and the timer as PWM to realize an analog output.

Today the developing time was often the most costly part. And the pantyhose 8051 assemblers/compilers fits for all of your small and big applications. Using always the same developing tools can hold the developing time very short.

The only missing thing was, that for extremely small size no 8051 with internal clock and power on reset was available.

But this niche can easy be filled with the AVR tiny series (ATTINY12, ATTINY15). Unfortunately they are more expensive as the AT89C1051 part, so only size reduction, but no cost reduction can be achieved.

For bigger projects the AVR series looks unqualified, because they have no different interrupt priorities. And on more complex applications some time critical tasks need always a higher priority than other interrupts.
Building different priorities in software was a hard thing on the AVR and need often many of the costly interrupt handling time.
So bigger projects on the AVR need more Flash size and also slower executed than on the 8051.


I give also a try to the PIC family (SX18), but I found no way to use external interrupts and lose no timer interrupt at the same time. But this was impossible, since always the same interrupt vector was used and no timer interrupt pending flag exist, which can be checked.
In my opinion the possibility to lose interrupts point to an extremely bad design and so I stopped further using of the PICs.




Peter