A brief survey on MCUs

1. Recently,I have done some sketchy investigation of MCUs.?A full list is not possible,and I focus on four major ones: Microchip,Atmel,Arm,and Renesas.?The vendors,applications are discussed bellow. Renesas is #1 MCUs vendor,Microchip is #1 8-bit MCUs vendor,Atmel is a vendor with fastest growth in 8-bit MCUs,and Arm is #1 used IP core of architecture.

2. Classes of MCUs

? ? ? The MCUs could be split into three kinds,low end,medium end and high end. Low end means the 8-bit MCUs,medium end means 16/32-MCUs,and high end means the 32-bit MCUs (maybe more than one core right now). 16-bit MCUs may be ignorable,for they seem to come to end,for the existence of 8-bit MCUs and the lower cost of 32-bit MCUs.?

? ? ?Low end MCUs focus on low cost,and are applied in small situations,like IC cards,pseudo random number generator,lighting devices,motor controller,etc. Ex,Arm Cortex-M series of Arm(use the Thumb/Thumb2 instruction set),pic 16/18/24 series of Microchip,80C51,AVR-8 of Atmel,RL78 of Renesas.

? ? ? Medium end MCUs focus on higher performance and applied in more complicated situations,like remoter monitor,IP camera,set op boxes,digital TV,media players,cameras,hard disk drives,networking,printing,dependable systems in medical/industrial/automotive,IH cooking heaters,air conditioners,washing machines,digital cameras. Ex,Cortex-R series of Arm,pic 32 series of Microchip,AVR-32 of Atmel,RX of Renesas.

? ? ? High end MCUs focus on more performance (usually a rich OS platform is supported),and applied in situations like: smartphones,mobile computing,set-up boexes,and even servers. For example,the iphone 4,ipad2,and Sansung waver use Cortex-A8. Ex,Cotex-A series of Arm,VR of Renesas.

3. Hardware features

? ?Low end MCUs: are basically so simple that,no cache,up to 128K/536K flash memory,up to 4k/96K ram,optional 4K EEPROM.?
? ?pic8:?no cache,up to 128K flash memory,up to 4K ram
? ?pic24:?no cache,up to 536K flash memory,up to 96K ram,4K EEPROM.?
? ?tinyAVR8: no cache,up to 8K flash,upto 0.5K sram,up to 512B EEPROM.
? ?megaAVR8: no cache,up to 128K flash,no ram.
? ?AVR XMEGA8: no cache,up to 256K flash,up to 16K sram,up to 4K EEPROM.
? ?78K0-8: no cache,up to 60K flash,up to 3K ram.
? ?RL78-16: no cache,up to 512K flash,up to 32K ram.

? ?Medium end MCUs:?
? ?Cotex-R: optinal 4-64K cache.
? ?pic32: no cache,?up to 512K flash,up to 128K sram,prefetch buffer cache.
? ?AVR32: no cache,up to 128K dram
? ?RX-32: no cache,up to 32K ram.? ?? ?

? ?High end MCUs: ? ?Cotex-A: ?up to 64K L1 cache,up to 4M L2 cache,up to 1T memory is accessible. ? ?VR-64: ?2-way,up to 32K I/D cache.