| ??? 04/15/09 18:59 Read: times |
#164629 - No, it should NOT be just that ... Responding to: ???'s previous message |
Per Westermark said:
Richard said:
When the ARM with 32 KB of code space + 8 KB of data space can support the same task at the same cost with the same effective performance as the 805x, the 805x will truly be "circling the bowl." In theory, the ARM will be more development-friendly. That shoud be "When the ARM with whatever amount of code and RAM space can support the same task at the same cost..." The actual size of flash or RAM is irrelevant as long as there is enough, and the price is acceptable. It is a well-known fact that the cost of a microcontroller do not follow the size of the memory regions. More memory is normally followed by more peripherals and gives a higher price within the same family from the same manufacturer. But as soon as you move to another family from the same or other manufacturer, the price correlation fails. I'm currently looking at a move from one NXP ARM family to another. I gain more RAM and more peripherals, but since I move to a newer architecture I'll save money at the same time. When making a comparison based on consumed resources, the relative performance has to be considered as well. If I can use an ARM at the same cost but have to tolerate performance that fails to meet my requirements, I'm unable to "get by." If an ARM chip with 64TB of memory on-chip costs the same as an 805x with only 64KB (the most it's normally likely to have) and both of them cost within 1% (more if volume is low) of the same amount, then the ARM would certainly be my choice, since the tools are better, the architecture is more flexible, etc. The fact that the architecture is newer, however, is no advantage. In general, if the system cost and performance resulting from a given MCU choice is better, than the choice is easy. Typical product lifespan, these days, is about three years. If the product works as intended, then maintainability isn't an issue if the product works properly. If it has to be changed within the three year product life, well, it's badly designed/debugged/tested and the people in charge, and the product itself, should be replaced. RE |
