PicoBlaze是由Xilinx公司的Ken Chapman設(shè)計并維護(hù)的一款8bit的微控制器軟核，可以嵌入到Cool Runner II、 Virtex-E，Virtex-II(Pro) 和 Spartan3(E)的CPLD以及FPGA中。 首先說一下PicoBlaze這個名字。我們知道：Xilinx主推的32-bit RISC嵌入式軟核叫MicroBlaze，非官方有時也可寫成uBlaze，用來表示該軟核非常之小。Xilinx推出比它更小的軟核就是PicoBlaze了。學(xué)過電路的人都知道，電容單位里有個量級叫皮法。

也就是pF。這里的p就是Pico-的意思，它表示10的負(fù)12次方這樣一個數(shù)量級。而PicoBlaze這個軟核呢，也的確是名符其實。將它實現(xiàn)在XC3S500E的FPGA中，只用到了96個SLICE，也就是只占用到了5%的邏輯資源的樣子。
不過麻雀雖小，性能卻挺強(qiáng)大的。對于整個指令集，PicoBlaze執(zhí)行一條指令需要2個時鐘周期。即使這樣。

在Spartan3E Starter Kit板上以50MHz的時鐘為例，PicoBlaze也能達(dá)到25MIPS的性能，對于要求不是太高的應(yīng)用場合。PicoBlaze是一個不錯的選擇。而且在某索愛手機(jī)游戲些特殊的應(yīng)用場合下。

還可以實現(xiàn)例化多個PicoBlaze軟核來達(dá)到設(shè)計目的。
盡管PicoBlaze的定義是Microcontroller(ug129就是這樣寫的)，但是根據(jù)Ken Chapman在PicoBlaze的參考設(shè)計里提到的，PicoBlaze實際上是常數(shù)碼可編程的狀態(tài)機(jī)(KCPSM, short for Konstant Code Programmable State Machine)。巧合的是，我們也可將其稱之為Ken Chapman's Programmable State Machine, 以示紀(jì)念，呵呵！從它參考設(shè)計中附帶的PSM代碼中可以看到，針對PicoBlaze編寫的代碼大部分都是由Constant，各個函數(shù)段間的跳轉(zhuǎn)以及中斷服務(wù)例程(ISR, Interrupt Service Routine)構(gòu)成的。這些代碼的執(zhí)行都是順序的，盡管這似乎與FPGA能有效執(zhí)行操作的特點不同。
但是在某些場合。
用PicoBlaze卻能夠簡化設(shè)計，而又不失性能。
在Xilinx的官方論壇上，Ken Chapman列具了如下可以采用PicoBlaze的應(yīng)用場景：
LED flasher (已有參考設(shè)計)
PWM control and even generation (KHz PRF for motors and brightness control) (已有參考設(shè)計)
Switch monitor.
UART interface and simple command/status terminal (已有參考設(shè)計)
LCD character module display interface and control (已有參考設(shè)計)
SPI master (i.e. FLASH controller for Spartan-3AN).
I2C master.
Calculator (XUP-San Jose State University)
Audio DSP processor (typically up to 48KHz sample rate and may utilise a hardware multiplier as a peripheral)
DTMF tone telephone dialer including sine wave generation (8KHz sample rate)
System monitoring (e.g. temperature monitor and fan control).
Motor control
Rotary encoder interface (Spartan3E Build-in Demo)
Calculator for frequency synthesizer.
Calculator for filter coefficient generation.
Emulation of a different micro controller (可用來模擬8051,By Roman-Jones,Inc)
PID control.
Mouse/Keyboard interface.
Keypad scanner
Power supply monitoring and control.
Servo control.
Built-in test equipment (on-chip monitor).
Configuration management (ICAP port)
Design Authentication Processor (已有參考設(shè)計)
Implementing peripherals for MicroBlaze or PPC.
Interrupt controller for MicroBlaze or PPC.
來看看PicoBlaze做到了什普通發(fā)光二極管電流么吧：
在美國紐約的時代廣場的JP Morgan Chase大樓，有一塊碩大的LED廣告屏。這塊廣告屏在當(dāng)時(2004年)是世界上最大的高亮解析度的LED顯示屏，而驅(qū)動這塊顯示屏的，正是PicoBlaze，整個設(shè)計中用到了10塊XC2V1000 Virtex-II, 323塊XC3S200 Spartan-3, 以及333塊XCF00 Platform Flash PROM和3800塊XC9572XL72 PLD宏單元。使用到的PicoBlaze的數(shù)量更是超過了1000個。

引用設(shè)計主管的話：
"The favorite toy in our Xilinx bag-of-tricks is the PicoBlaze processor. We could not have completed the project in the time allowed without extensive use of the PicoBlaze processor. The sign contains an impressive count of more than 1,000 of these embedded processors, with nine different designs.PicoBlaze processors provide efficient logic resource utilization by time-multiplexing logic circuits. The PicoBlaze processor also provides a quick and easy way to develop control functions. The alternative would be to build a custom state machine for each function. The PicoBlaze processor is a programmable state machine, meaning that the state machine is already built; one just has to program it."
Jason Daughenbaugh, Sr Design Engineer, Advanced Electronic Designs (AED)
Application: Large LED display for JP Morgan in Times Square, NY
因此，千萬不要因為當(dāng)今流行32bit的嵌入式CPU而忽視了PicoBlaze這位小兄弟。