' MCP 4822 dual 12 bit DAC demo program
'
cpu 48
option explicit
option default FLOAT
'
' Pin assignments
'
' DAC pin 1 = VDD
const cs=23 'DAC pin 2 connected to digital output on micromite
' Pin 25 = SCK : DAC Pin 3
' Pin 3 = SDI : DAC Pin 4
const ldac=24 ' DAC Pin 5 connected to digital output on micromite
const voutb=7 ' DAC Pin 6 connected to analogue input on micromite
' DAC Pin 7 = GND
const vouta=6 ' DAC Pin 8 connected to analogue input on micromite
'
'Pin use
'
setpin cs, dout
setpin ldac, dout
setpin vouta,ain
setpin voutb,ain
'
DIM gain as integer 'DAC output scale, can be 1 or 2, VDD to DAC must be at least 4.15V for gain 2 to use full output range
'
dim DACa ,DACb
dim voltage
dim i as integer
INIT:
pin(cs)=1 'set chip select inactive
pin(ldac)=1 'set ldac inactive
spi open 5000000,0,16 '5 MEG, 16 bit transfer, CLK active high, data on leading edge
'
MAIN:
for gain=1 to 2
Print "Gain = ",gain
print "Measurement resolution is 3.3/1024 = 0.003V"
if gain=1 then print "DAC resolution is 2.048/4096 = 0.0005V"
if gain=2 then print "DAC resolution is 4.096/4096 = 0.001V"
print " DAC-A ADC DAC-B ADC"
for i=0 to 20
voltage=i*gain*0.1
DACa=setdac(0,gain,voltage)
DACb=setdac(1,gain,2*gain-voltage)
print str$(DACa,1,4),str$(pin(vouta),1,4),str$(DACb,1,4),str$(pin( voutb),1,4)
i=i+(0.1*gain)
pause 500
NEXT i
print ""
next gain
end
'
' Function to set output on one of the DAC channels
'
function setdac (DAC as integer, dacgain as integer, volts)
local dacdata as integer,FuncRet as integer
dacdata=cint(volts * 2000 / dacgain)
if dacdata>4095 or dacdata<0 or DAC<0 or DAC>1 or gain<1 or gain>2 then
setDAC=0
exit function
endif
setdac= dacdata /2000 * dacgain
if DAC=0 then
dacdata=dacdata or &B0011000000000000
else
dacdata=dacdata OR &B1011000000000000
endif
if gain=2 then dacdata=dacdata and &B1101111111111111 'clear bit 13 to set gain of 2
pin(cs)=0 'enable data reception
FuncRet=spi(dacdata) 'output the control bits and the data
pin(cs)=1 'disable data reception
pulse ldac,0.005
end function

function setdac (DAC as integer, dacgain as integer, volts)
local dacdata as integer,FuncRet as integer
dacdata=cint(volts * 2000 / dacgain)
if dacdata>4095 or dacdata<0 or DAC<0 or DAC>1 or dacgain<1 or dacgain>2 then
setDAC=0
exit function
endif
setdac= dacdata /2000 * dacgain
if DAC=0 then
dacdata=dacdata or &B0011000000000000
else
dacdata=dacdata OR &B1011000000000000
endif
if dacgain=2 then dacdata=dacdata and &B1101111111111111 'clear bit 13 to set gain of 2
pin(cs)=0 'enable data reception
FuncRet=spi(dacdata) 'output the control bits and the data
pin(cs)=1 'disable data reception
pulse ldac,0.005
end function

function setdac (DAC as integer, dacgain as integer, volts)

function setdac(DAC as integer, dacgain as integer, volts)

dacdata=Cint(volts * 2000 / dacgain)

'
' MCP 4822 dual 12 bit DAC demo program by matherp@TBS
' modified for Maximites MMBasic 4.5D (twofingers@TBS 2/2015)
' http://www.thebackshed.com/forum/forum_posts.asp?TID=7154&KW =4822
'
' 4822-Registers
' A/B -- GA SHDN D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
' Bit 15 00
'
' Provided AS IS without any warranty.
' Use it at your own risk. All information is provided for
' educational purposes only!

'
' Pin assignments on MCP4822
'

' DAC pin 1 = VDD 3V3! With gain x2 and VDD 5V you will destroy your non 5V tolerant MM inputs!!
cs =11 ' DAC pin 2 output(MM)
SCK =12 ' DAC Pin 3 output(MM)
SDI =13 ' DAC Pin 4 output(MM)
ldac=14 ' DAC Pin 5 output(MM)
voutb=3 ' DAC Pin 6 input(MM)
' DAC Pin 7 = GND
vouta=2 ' DAC Pin 8 input(MM)
RX =15 ' for SPI()

'
'Pin use
'
' CS, SCK, SDI, lDac can be any DOUT, RX any DIN
SetPin cs, dout
SetPin SCK, dout
SetPin SDI, dout
SetPin ldac, dout
SetPin vouta,ain
SetPin voutb,ain
SetPin RX, din ' N/C, unused


Dim gain
Dim DACa ,DACb
Dim voltage
Dim i

INIT:
Pin(cs)=1 'set chip select inactive
Pin(ldac)=1 'set ldac inactive



MAIN:
For gain=1 To 2
Print "Gain = ",gain
Print "Measurement resolution is 3.3/1024 = 0.003V"
If gain=1 Then Print "DAC resolution is 2.048/4096 = 0.0005V"
If gain=2 Then Print "DAC resolution is 4.096/4096 = 0.001V"
Print " DAC-A ADC -|- DAC-B ADC"
For i=0 To 20
voltage=i*gain*0.1
DACa=setdac(0,gain,voltage)
DACb=setdac(1,gain,2*gain-voltage)


Print " "Format$(DACa,"%0.1f")" "Format$(Pin(vouta),"%0.3f")" -|- ";
Print Format$(DACb,"%0.1f")" "Format$(Pin(voutb),"%0.3f")
Pause 00
Next i
Print ""
Next gain

' Speedtest
Dim a(2000)
Timer=0
For i=1 To 2000
Next i
Print Timer

For i = 1 To 2000
a(i)=i/1000
Next i

Timer=0
junk=0
For i=0 To 2000
SetdacA(a(i))
Next i
Print
Print Timer

' lets save some power
Pause 2000
ShutDnDac(0)
ShutDnDac(1)
End
'-------------------------------------------------------


'
' Sub to set DAC A channel, optimised for speed (~2000 op/sec)
' no error handling!
Sub SetdacA(v) 'v=volt, DAC=A(or 0), Gain=2
Pin(cs)=0:junk=SPI(rx,SDI,SCK,v*1000 Or &B0001000000000000,,,16):Pin(cs)=1
Pulse ldac,0.005
End Sub


'
' Sub to shutdown the DAC 0 or 1 (A or B)
'
Sub ShutDnDac(DAC)
Local junk
Pin(cs)=0
If DAC=0 Then
junk=SPI(rx,SDI,SCK,&B0000000000000000,,,16)
Else
junk=SPI(rx,SDI,SCK,&B1000000000000000,,,16)
EndIf
Pin(cs)=1
Pulse ldac,0.005
End Sub


'
' Function to set output on one of the DAC channels
'
Function setdac(DAC, dacgain, volts)
Local dacdata, junk
dacdata=Cint(volts * 2000 / dacgain)
If dacdata>4095 Or dacdata<0 Or DAC<0 Or DAC>1 Or dacgain<1 Or dacgain>2 Then
setDAC=0
Exit Function
EndIf
setdac= dacdata /2000 * dacgain
If DAC=0 Then
dacdata=dacdata Or &B0011000000000000
Else
dacdata=dacdata Or &B1011000000000000
EndIf
If dacgain=2 Then dacdata=dacdata And &B1101111111111111

Pin(cs)=0
junk = SPI(rx,SDI,SCK,dacdata,,,16) 'using defaults: speed=H (3 MHz), mode=3
Pin(cs)=1
Pulse ldac,0.005
End Function