1、第十三章 基于Picoblaze的PWM控制器設(shè)計背景介紹該實驗使用Xilinx的嵌入式軟核Picoblaze實現(xiàn)了一個12路通道的256階PWM控制器。實驗目標通過完成這個實驗，你將能得到如下技能：· 熟悉PWM控制器，并對其關(guān)鍵參數(shù)（周期和占空比）有較深認識· 運用Picoblaze指令集完成PWM控制器的匯編代碼· 運用KCPSM3編譯器完成匯編代碼的編譯工作· 運用Xilinx ISE對嵌入式軟核Picoblaze完成例化· 在上位機上熟練配置超級終端并與BASYS開發(fā)板完成串口通信· 通過超級終端對PWM控制器進行控制目標平

2、臺硬件平臺：BASYS開發(fā)板軟件平臺：Xilinx ISE11.1 KCPSM3實驗步驟該實驗的開發(fā)包括以下五個步驟： 1. 系統(tǒng)分析2. 系統(tǒng)軟件開發(fā)3. 建立系統(tǒng)工程并完成例化4. 系統(tǒng)工程綜合、翻譯、映射、布局布線并生成可執(zhí)行文件 5. 硬件測試 通過以上步驟，你將可以一步一步的將該實驗在Basys板上實現(xiàn)并運行。如果你認為自己某些地方有足夠的了解，那么可以跳過那些步驟直接進行下一步的開發(fā)。系統(tǒng)分析步驟 1該實驗設(shè)計了一個基于嵌入式軟核Picoblaze的12路通道PWM控制器，每路通道的占空比均可在0255之間任意設(shè)定。系統(tǒng)可通過上位機的超級終端與BASYS開發(fā)板完成串口通信，通過該串

3、口通信完成各路PWM通道的占空比參數(shù)設(shè)置。12路通道中的8路通過BASYS開發(fā)板上的八個LED燈的亮度來顯示其占空比設(shè)置變化，另外4路則通過擴展口輸出。實驗的硬件系統(tǒng)框圖如圖1所示。圖1圖1中的PmodRS232是串口模塊。實驗中的兩個關(guān)鍵參數(shù)是脈沖重復頻率（PRF）和分辨率（resolution）分別為1KHz和8bit（1/256）。如圖2所示。圖2 由上所述，實驗需要將嵌入式系統(tǒng)picoblaze例化到FPGA中，其框圖如圖3所示。圖3軟件開發(fā)步驟 2當你完成系統(tǒng)分析后，你必須進行軟件開發(fā)。軟件開發(fā)包括匯編代碼的開發(fā)和Verilog代碼的開發(fā)。系統(tǒng)的關(guān)鍵代碼設(shè)計如下所示。1. 計數(shù)器中斷

4、的Verilog源代碼設(shè)計實驗中系統(tǒng)時鐘為50MHz，采用模196的計數(shù)器中斷來對完成PWM控制器的PRF和resolution設(shè)置。以下是對應的Verilog的源代碼（請補充）。 always (posedge clk) beginif(interrupt_count=195) begin interrupt_count <= 0; interrupt_event <='1; end else begininterrupt_count <= interrupt_count + 1; interrupt_event <= 0;end if (interrupt_

5、ack=1) interrupt <= 0; elsif (interrupt_event=1) interrupt <=1; else interrupt <= interrupt; end 2.串口通信的Verilog源代碼設(shè)計設(shè)置UART通信的波特率為9600，以下是對應的Verilog的源代碼（請補充）。always (posedge clk) begin if（ baud_count=325）begin baud_count <= 0; en_16_x_baud <= 1; end else begin baud_count <= baud_cou

6、nt + 1; en_16_x_baud <='0; end end 3. PWM控制器占空比設(shè)置的匯編源代碼設(shè)計實驗對PWM控制器的占空比初始化設(shè)置，以下是對應的psm的源代碼（請補充）。LOAD s0, 05 ;5/256 = 2% STORE s0, PWM_channel0 LOAD s0, 0D ;13/256 = 5% STORE s0, PWM_channel1 LOAD s0, 14 ;26/256 = 8% STORE s0, PWM_channel2 LOAD s0, 26 ;38/256 = 15% STORE s0, PWM_channel3 LOAD s

7、0, 40 ;64/256 = 25% STORE s0, PWM_channel4 LOAD s0, 58 ;88/256 = 34% STORE s0, PWM_channel5 LOAD s0, 80 ;128/256 = 50% STORE s0, PWM_channel6 LOAD s0, FF ;255/256 = 99.6% Maximum possible STORE s0, PWM_channel7 ; ; Initial values for simple outputs match documentation example ; LOAD s0, 11 ;17/256 =

8、 7% STORE s0, PWM_channel8 LOAD s0, BC ;188/256 = 73% STORE s0, PWM_channel9 LOAD s0, EF ;239/256 = 93% STORE s0, PWM_channel10 LOAD s0, 22 ;34/256 = 13% STORE s0, PWM_channel114. 中斷服務程序匯編源代碼設(shè)計中斷的psm的源代碼（請補充）。ISR: STORE s0, ISR_preserve_s0 ;preserve registers to be used STORE s1, ISR_preserve_s1 STO

9、RE s2, ISR_preserve_s2 ;Determine the number of steps currently through the 1ms PWM cycle FETCH s1, PWM_duty_counter ;read 8-bit counter of steps ADD s1, 01 ;increment counter (will roll over to zero) STORE s1, PWM_duty_counter ;update count value in memory for next interrupt. ;Read duty factor for

10、each channel and compare it with the duty counter and set or ;reset a bit in register s2 accordingly. FETCH s0, PWM_channel11 ;read desired setting of pulse width COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM_channel10 ;read desire

11、d setting of pulse width COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM_channel9 ;read desired setting of pulse width COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM

12、_channel8 ;read desired setting of pulse width COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 OUTPUT s2, simple_port ;drive pins on connector J4 FETCH s0, PWM_channel7 ;read desired setting of pulse width COMPARE s1, s0 ;set carry flag if duty fa

13、ctor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM_channel6 ;read desired setting of pulse width COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM_channel5 ;read desired setting of pulse width COMPARE s1, s0 ;set

14、 carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM_channel4 ;read desired setting of pulse width COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM_channel3 ;read desired setting of pulse wid

15、th COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM_channel2 ;read desired setting of pulse width COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM_channel1 ;read desire

16、d setting of pulse width COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 FETCH s0, PWM_channel0 ;read desired setting of pulse width COMPARE s1, s0 ;set carry flag if duty factor > duty counter SLA s2 ;shift carry into register s2 OUTPUT s2, LE

17、D_port ;drive LEDs FETCH s0, ISR_preserve_s0 ;restore register values FETCH s1, ISR_preserve_s1 FETCH s2, ISR_preserve_s2 RETURNI ENABLE編譯匯編代碼步驟 3具體步驟如下1.選擇“開始”“運行”，如圖4所示。在對話框輸入cmd命令后點擊確定。圖42.使用DOS命令CD將目錄指向匯編程序所在文件夾下，鍵入 kcpsm3 pwm_ctrl.psm命令后回車，如圖5和圖6所示。圖5圖6建立系統(tǒng)工程步驟 41.建立新工程，如圖7和圖8圖7 圖82.加入源文件到工程，如圖

18、9，圖10和圖11圖9圖10圖11綜合、翻譯、映射、布局、布線并生成可執(zhí)行文件步驟 5圖12圖13下載可執(zhí)行文件 步驟 61所示。 圖14圖15圖16圖17圖18圖19圖20圖21硬件資源耗用如表1所示表1 硬件資源耗用表Logic UtilizationUsedAvailableUtilizationNote(s)Number of Slice Flip Flops1611,9208% Number of 4 input LUTs2661,92013% Number of occupied Slices16396016% Total Number of 4 input LUTs2831,92014% N