The 18F2550 is the same as the 18F4550 except it is in a 28 pin poackage and has no SSP port but it does have the USB port.
The 18F2550 is a microcontroller for more demanding applications having lots
of program memory (16k) and RAM (2k) and a full USB interface - V2.0 Compliant (Low Speed
(1.5Mb/s) and Full Speed (12Mb/s).
You can run the external clock up to 48MHz and if using a lower external clock the internal PLL will run high enough so that the USB clock operates at the correct speed. So this microcontroller can operate at 48MHz! - but remember the internal clock is Fosc/4 so the MIPS rate is 12MIPSi.e. the real operating frequency is 12MHz.
It comes in a 28 pin package and is also optimized for C programming (75 standard + 8 extra instrucitons) and it uses nano watt technology.
Once again the device uses ICSP for programming and you can program it in circuit if you design the interface correctly.
As with all the 18F series there is a built in 8x8 hardware multiplier so your calculations will run much faster.
Note: Unlike the mid range PIC micros the 18F series have a 31 word stack so you can make nested function calls without worrying about running out of return stack space.
For a summary of each peripheral block click here.
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