【RPi PICO】DDS正弦发生器和双路PWM输出

dcexpert

【RPi PICO】DDS正弦发生器和双路PWM输出 [复制链接]

 

来自：https://forum.micropython.org/viewtopic.php?t=9945&p=55587#p55587

 

DDS 的正弦发生器，使用第二个内核生成。为了实现更高的分辨率和更高的频率，它增加了2个PWM信号，每个6位。 

 

婵犵數濮烽弫鍛婃叏閻戣棄鏋侀柛娑橈攻閸欏繐霉閸忓吋缍戦柛銊ュ€块弻锝夊箻瀹曞洤鍝洪梺鍝勵儐閻楁鎹㈠☉銏犵闁绘劕顕▓銈夋⒑濞茶骞楅柟鐟版喘瀵鎮㈤搹鍦紲闂侀潧绻掓慨鐢告倶閸儲鈷戦柛婵嗗椤忋儵鏌涙惔锝嗘毈鐎殿喖顭锋俊鎼佸煛閸屾矮绨介梻浣呵归張顒傜矙閹达富鏁傞柨鐕傛嫹

登录后复制

# DDS Sine Generator in second core by CWE
# Example using Double PWM
# http://www.openmusiclabs.com/learning/digital/pwm-dac/dual-pwm-circuits/index.html 100k and 1.5k + 4.7nF

import time, _thread, sys
from machine import Pin, PWM
import math
import uarray

# Construct PWM object, with LED on Pin(25).
pwmA = PWM(Pin(15, Pin.OUT)) # upper 6 bits
pwmB = PWM(Pin(14, Pin.OUT)) # low 6 bits


# Set the PWM frequency.
pwmFreq= int(125_000_000/64) # 6 bit
pwmA.freq(pwmFreq)
pwmB.freq(pwmFreq)
pwmA.duty_u16(31<<10)
pwmB.duty_u16(31<<10)

sineBufLen= 6249 #1kHz: 6249
sineBuf=uarray.array("H",range(0,sineBufLen))
for x in range(0,sineBufLen):
    xr= x/sineBufLen*2*math.pi
    sineBuf[x]= 2047+int(2047*math.sin(xr)) # 12 bit resolution
    #print(sineBuf[x])

pwmA.duty_u16(0<<10)
pwmB.duty_u16(0<<10)

ddsCtrl = uarray.array('i',[
    0x40050000 + 0x98, # 0 cc7
    sineBufLen, # 4
    1, # 8 
    int((1<<16)*1.0) # 12 1=run, step in half
    ])

@micropython.asm_thumb
def dds(r0, r1): # Buffer, ctrl-array

    mov(r2,r0) # Buffer Start Address
    ldr(r5, [r1,4]) # buffer length
        
    ldr(r4, [r1,0]) # pwm counter compare register
    ldr(r7, [r1,12]) # step index fine
    
    mov(r3,0) # Buffer Index fine
    
    label(nextVal)
    
    lsr(r0,r3,16) # index coarse 
    lsl(r0,r0,1) # index coarse half words
    add(r0,r0,r2)
    ldrh(r0,[r0,0]) # read buffer     regPoke(0x40050000 + 0x98, ((a>>6)<<16) + (a&63))
    lsl(r6,r0,26) # get the lowest 6 bit
    lsr(r0,r0,6) # shift bits right (upper)
    lsl(r0,r0,16)
    
    lsr(r6,r6,26) # lower 6 bits
    add(r0,r0,r6)
    
    str(r0,[r4,0])
    #b(retu)
    
    add(r3,r3,r7) # next buffer index fine
    lsr(r0,r3,16)
   
    cmp(r5,r0) # end not yet reached
    bhi(nextVal)
    
    lsl(r0,r5,16)
    sub(r3,r3,r0)    
    mov(r0,r3)
    
    ldr(r7, [r1,12]) # reload step index repeat?
    cmp(r7,0)
    bne(nextVal)
    
    label(retu)

    


@micropython.asm_thumb
def regPeek(r0): # Address
    mov(r1,r0)
    ldr(r0,[r1,0])

@micropython.asm_thumb
def regPoke(r0, r1): # Address, Data
    str(r1,[r0,0])
    mov(r0,r1)
    
def regSet(adress, mask):
    regPoke(adress, regPeek(adress) | mask)

def setF(f):
    ddsCtrl[3]=int(f/1000*(1<<16))

#sineBuf[0]=1<<6
#print(dds(sineBuf, ddsCtrl))
_thread.start_new_thread(dds, (sineBuf, ddsCtrl))


try:
    while True:
        f=10
        while f<25_000:
            setF(f)
            time.sleep(.2)
            print(f, end=" ")
            f=f*1.5849 #math.sqrt(10)
        
except KeyboardInterrupt:
    ddsCtrl[3]=0
    sys.exit()

   
"""
x=0
delta=10


while True:
    x+= delta
    if x>(sineBufLen-1):
        x-=sineBufLen
    a= sineBuf[x]
    #pwmA.duty_u16( (a<<4) & (255<<8)) # upper 6 bit
    #pwmB.duty_u16( (a<<10) & (255<<8)) # lower 6 bit
    regPoke(0x40050000 + 0x98, ((a>>6)<<16) + (a&63))
    #regPoke(0x40050000 + 0x98, ((a>>6)<<16)) 
 """  

 

Jacktang

DDS 的正弦发生器

谢谢分享

w494143467

没玩，不过点个赞！！！