【正文】 Inc. 2022. Slide 30 PWM 時(shí)鐘選擇 – 分頻寄存器 (3 of 4) 總線時(shí)鐘 fBus Divide by Prescaler Taps: 2 4 8 16 32 64 128 8Bit Down Counter Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 PWMSCLx 分頻值 SxC l o c kxC l o c kP W M S C LxP W M S C LxxC l o c kSxC l o c k_2_2__????PWMSCLx = $00 ? PWMSCLx value is 256 可在任意時(shí)刻讀寫(xiě) ! x = A or B / 2 Clock Sx Clock x Clock x = fBus / PWMPRCLK Count = 1 PWMPRCLK @ $_03 PWMSCLB @ $_09 PWMSCLA @ $_08 例如 : 要求 : Clock Sx = 1 kHz 總線時(shí)鐘 = 16 MHz Prescaler = 128 ? Prescaler = 64 Clock x = 125 kHz Clock x = 250 kHz PWMSCLx = 63 ? PWMSCLx = 125 ? Clock Sx = 992 Hz Clock Sx = 1000 Hz TM Freescale Semiconductor Confidential and Proprietary Information. Freescale? and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. 169。 Freescale Semiconductor, Inc. 2022. Slide 31 PWM 時(shí)鐘選擇寄存器 (4 of 4) PCLK6 PCLK5 PCLK4 PCLK3 PCLK2 PCLK1 PCLK0 R W Reset: 0 0 0 0 0 0 0 0 PWMCLK @ $_02 PCLK7 選擇時(shí)鐘源 : PCLK0 = 1。 // SA is source of ch 0 PCLK6 = 0。 // B is source of ch 6 PWMCLK = 0x11。 // all channels 軟件示例 Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 0 PCLK5 —通道 5時(shí)鐘選擇 1 =時(shí)鐘源為 SA 0 =時(shí)鐘源為 A PCLK4 —通道 4時(shí)鐘選擇 1 =時(shí)鐘源為 SA 0 =時(shí)鐘源為 A PCLK3 —通道 3時(shí)鐘選擇 1 =時(shí)鐘源為 SB. 0 =時(shí)鐘源為 B PCLK2 —通道 2時(shí)鐘選擇 1 =時(shí)鐘源為 SB 0 =時(shí)鐘源為 B PCLK1 —通道 1時(shí)鐘選擇 1 =時(shí)鐘源為 SA 0 =時(shí)鐘源為 A PCLK0 —通道 0時(shí)鐘選擇 1 =時(shí)鐘源為 SA 0 =時(shí)鐘源為 A PCLK7 — 通道 7時(shí)鐘選擇 1 = 通道 7的時(shí)鐘源為 SB 0 =通道 7的時(shí)鐘源為 B. PCLK6 —通道 6時(shí)鐘選擇 1 =時(shí)鐘源為 SB. 0 =時(shí)鐘源為 B TM Freescale Semiconductor Confidential and Proprietary Information. Freescale? and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. 169。 Freescale Semiconductor, Inc. 2022. Slide 32 PWMPERx PWMDTYx PWM 計(jì)時(shí)器通道 8Bit Counter PWMCNTx 8Bit Compare = PWMDTYx 8Bit Compare = PWMPERx PWMCNT0 @ $_0C PWMCNT1 @ $_0D PWMCNT2 @ $_0E PWMCNT3 @ $_0F PWMCNT4 @ $_10 PWMCNT5 @ $_11 PWMCNT6 @ $_12 PWMCNT7 @ $_13 PWMDTY0 @ $_1C PWMDTY1 @ $_1D PWMDTY2 @ $_1E PWMDTY3 @ $_1F PWMDTY4 @ $_20 PWMDTY5 @ $_21 PWMDTY6 @ $_22 PWMDTY7 @ $_23 PWMPER0 @ $_14 PWMPER1 @ $_15 PWMPER2 @ $_16 PWMPER3 @ $_17 PWMPER4 @ $_18 PWMPER5 @ $_19 PWMPER6 @ $_1A PWMPER7 @ $_1B 極性位 Polarity Bit = 1 ? Duty = High Time Channel x x = 0 ... 7 Double Buffered Double Buffered ? PWMDTYx PWMPERx 占空比寄存器 周期寄存器 TM Freescale Semiconductor Confidential and Proprietary Information. Freescale? and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. 169。 Freescale Semiconductor, Inc. 2022. Slide 33 使能 /禁止 PWM PWME6 PWME5 PWME4 PWME3 PWME2 PWME1 PWME0 R W Reset: 0 0 0 0 0 0 0 0 PWME @ $_00 PWME7 1 = 通道 x 使能 . 下一個(gè)時(shí)鐘開(kāi)始輸出 PWM 0 = 通道 x禁止 通道 7 通道 6 通道 0 ... 使能 /禁止 PWM 通道 : PWME5 = 1。 // Enable PWM channel 5 PWME3 = 0。 // Disable PWM channel 3 PWME = 0xFF // Enable all 8 PWM channels PWME = 0。 // Disable all 8 PWM channels 軟件示例 Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 0 TM Freescale Semiconductor Confidential and Proprietary Information. Freescale? and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. 169。 Freescale Semiconductor, Inc. 2022. Slide 34 PWM 極性選擇寄存器 PPOL6 PPOL5 PPOL4 PPOL3 PPOL2 PPOL1 PPOL0 R W Reset: 0 0 0 0 0 0 0 0 PWME @ $_00 PPOL7 1 = 在周期開(kāi)始時(shí)， PWM通道輸出為高電平，當(dāng)計(jì)數(shù)器等于占空比寄存器的值時(shí)，輸出為低電平 0 =在周期開(kāi)始時(shí)， PWM通道輸出為低電平，當(dāng)計(jì)數(shù)器等于占空比寄存器的值時(shí)，輸出為高電平 PWMDTYx PWMPERx PPOLx = 1 PWMDTYx PWMPERx PPOLx = 0 Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 0 通道 7 通道 6 通道 0 ... TM Freescale Semiconductor Confidential and Proprietary Information. Freescale? and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. 169。 Freescale Semiconductor, Inc. 2022. Slide 35 對(duì)齊方式選擇 左對(duì)齊 (1 of 3) Clock Source E = 100 ns Duty Cycle = 75 % Period = 400 ns %1 0 0_:1%1 0 0_:0),(_????????P W M P E R xP W M D T Y xC y c l eD u t yP o l a r i t yP W M P E R xP W M D T Y xP W M P E R xC y c l eD u t yP o l a r i t yP W M P E R xSBSABAC l o c kF r e q u e n c yP W M x時(shí)鐘源 = E = 10 MHz (100 ns period) PPOLx = 0 PWMPERx = 4 PWMDTYx = 1 PWMx 頻率 = 10 MHz/4 = MHz PWMx 周期 = 400 ns PWMx 占空比 = 190。*100% = 75% ? Start 分辨率？ TM Freescale Semiconductor Confidential and Proprietary Information. Freescale? and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. 169。 Freescale Semiconductor, Inc. 2022. Slide 36 對(duì)齊方式選擇 中央對(duì)齊 (2 of 3) PWMDTYx E = 100ns Period = PWMPERx*2 = 800 ns %1 0 0_:1%1 0 0_:02),(_?????????P W M P E R xP W M D T Y xC y c l eD u t yP o l a r i t yP W M P E R xP W M D T Y xP W M P E R xC y c l eD u t yP o l a r i t yP W M P E R xSBSABAC l o c kF r e q u e n c yP W M x時(shí)鐘源 = E = 10 MHz (100 ns period) PPOLx = 0 PWMPERx = 4 PWMDTYx = 1 PWMx 頻率 = 10 MHz/8 = MHz PWMx 周期 = 800 ns PWMx 占空比 = 190。*100% = 75% ? Start PWMDTYx E = 100ns PWMPERx PWMPERx Duty Cycle = 75% TM Freescale Semiconductor Confidential and Proprietary Information. Freescale? and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. 169。 Freescale Semiconductor, Inc. 2022. Slide 37 PWM 中央對(duì)齊使能寄存器 (3 of 3) CAE6 CAE5 CAE4 CAE3 CAE2 CAE1 CAE0 R