Difference between revisions of "Modulation Plugin"

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Line 108: Line 108:
 
*http://focus.ti.com/docs/prod/folders/print/ts5a1066.html
 
*http://focus.ti.com/docs/prod/folders/print/ts5a1066.html
 
*call sample
 
*call sample
 +
 
{|border="1" cellspacing="0" cellpadding="5"
 
{|border="1" cellspacing="0" cellpadding="5"
|+ Table 3.1 IC Requirements
+
|+  
! Part No. !! Description
+
! Part No. !! Operating Voltage !! Min Volt !! Max Volt !! Frequency response !! Propagation delay !! Min Temp !! Max Temp !! Pin !! Price(U.S.)
! Min Temp !! Max Temp !! Min Volt !! Max Volt !! Typ Cur !! Max Cur
 
 
|-valign="top"
 
|-valign="top"
| [http://ww1.microchip.com/downloads/en/DeviceDoc/70116F.pdf dsPIC30F5011-30I/PT] || uP
+
| [http://focus.ti.com/lit/ds/symlink/sn74lvc1g66.pdf SN74LVC1G66YZPR] || 1.65V~5.5V || -0.5V || 6.5V || 175MHz(3V) >300MHz(3V) (*1)
| -40<sup>o</sup>C || 85<sup>o</sup>C
+
| 0.8ns(3.3V)||-40<sup>o</sup>C || 85<sup>o</sup>C || 6-pin || 1:$0.48 100:$0.27
| 2.5V <sup>[1]</sup>|| 5.5V
 
|  145mA  || 217mA
 
|-
 
| [http://datasheets.maxim-ic.com/en/ds/MAX3222-MAX3241.pdf MAX3232ESE] || RS232 driver
 
| -40<sup>o</sup>C || 85<sup>o</sup>C
 
| 3.0V || 5.5V
 
| 0.3mA || 1.0mA
 
|-
 
| [http://www.national.com/ds.cgi/DS/DS3695.pdf DS3695N] || RS485 driver
 
| -40<sup>o</sup>C || 85<sup>o</sup>C
 
| 4.75V || 5.25V
 
| 42mA || 60mA
 
|-
 
| [http://focus.ti.com/lit/ds/symlink/dac6574.pdf DAC6574IDGS] || 10-bit Quad-DAC I<sup>2</sup>C
 
| -40<sup>o</sup>C || 105<sup>o</sup>C
 
| 2.7V || 5.5V
 
| 0.6mA || 0.9mA
 
|-
 
| [http://www.semiconductors.philips.com/acrobat/datasheets/74HC_HCT14_3.pdf 74HC14D] || Quad-Schmitt Trigger
 
| -40<sup>o</sup>C || 125<sup>o</sup>C
 
| 2.0V || 6.0V
 
| || 0.02mA
 
|-
 
| '''Overall''' ||  
 
| '''-40<sup>o</sup>C''' || '''85<sup>o</sup>C'''
 
| '''4.75V''' || '''5.25V'''
 
| || '''<300mA <sup>[2]</sup>'''
 
|-
 
| [http://ww1.microchip.com/downloads/en/DeviceDoc/70165E.pdf dsPIC33FJ128GP306-I/PT] || uP
 
| -40<sup>o</sup>C || 85<sup>o</sup>C
 
| 3.0V <sup>[1]</sup>|| 3.6V
 
| 74mA  || 250mA
 
|-
 
| [http://www.analog.com/UploadedFiles/Data_Sheets/ADM3485E.pdf ADM3485EARZ] || RS485 driver
 
| -40<sup>o</sup>C || 85<sup>o</sup>C
 
| 3.0V || 3.6V
 
| 1.1mA || 2.2mA
 
|-
 
| [http://ww1.microchip.com/downloads/en/DeviceDoc/21203N.pdf 24LC256-I/SN] || 256kBits I2C EEPROM
 
| -40<sup>o</sup>C || 85<sup>o</sup>C
 
| 2.5V || 5.5V
 
| 400uA || 3mA
 
 
|-
 
|-
| [http://www.national.com/ds.cgi/LM/LM3940.pdf LM3940IMP-3.3] || 5V-3.3V Regulator
+
| [http://focus.ti.com/lit/ds/symlink/sn74ahc4066.pdf SN74AHC4066DR] || 2V~5V || -0.5V || 7V || 30MHz(3V)
| -40<sup>o</sup>C || 125<sup>o</sup>C
+
| 0.8ns(3.3V)||-40<sup>o</sup>C || 85<sup>o</sup>C || 14-pin || 1:$0.55 100:$0.33
| 5.0V || 7.5V
 
| 10mA || 250mA
 
 
|-
 
|-
 
|}
 
|}
 +
(*1) different value of the RC circuit. ref. to the datasheet
  
 +
more information about the series 74 in wiki: http://en.wikipedia.org/wiki/7400_series
  
 
===op-amp buffer===
 
===op-amp buffer===

Revision as of 03:06, 9 July 2008

ToDos

  • make sure each components freq. response, to make sure the highest freq.
  • place DAC into this module board together, then only 4 wires(Vcc, I2C clk, Gnd & I2C data) from host.
  • understand all components
  • call sample
  • draw circuit and PCB and grounding problem
  • test by real circuit and firmware


Objectives

  • The modulation module is used to deliver a digital output signal with the following characteristics:
    • Square wave
    • Variable frequency (>1kHz)
    • Variable amplitude (0V - 2.5V)
  • interface to MCU which do the control


Q: Is square wave where the "Lo" time is always at "GND" OK? Q: If not, is a switch between "Lo is GND" vs. "Lo is negative Hi" OK? Or does "Lo" need to be independently controlled with another ADC?

Q: Will people be connecting a speaker directly to the output, requiring a relatively high-power output op amp such as the LM386N-3 ?

Software Solution

  • Timer Interrupt controlling I2C 10-bit DAC can only achieve frequency response of about 1kHz
    • 5byte/cmd
    • 8bit/byte
    • baudrate = 400kHz
    • This yields 10kHz (0.1ms)
    • As OS context switch is 10ms, set timer to 1ms (1kHz), so that 0.9ms can be used to process other tasks
  • Due to higher freq. response requirement, so using hardware to implement the clock


Hardware Solution

Circuit

                    +-----+            +--------+         +--------+
      I2C Bus       |     |            | Analog |         | Op-Amp |
  ------------+-----| DAC |------------| Switch |---------|        |---------Output
              |     |     |            +--------+         +--------+
              |     +-----+                |
              |                            |
              |     +--------------+       |
              |     | Programmable |       |
              +-----| Clock        |-------+
                    +--------------+
  

This architecture allows the square wave to run at a very high frequency, even with a slow I2C and a slow DAC.


Circuit Simulation by Paul Falstad's Web

  • Import the following
$ 1 5.0E-6 16.817414165184545 64 5.0 50
w 128 256 144 256 0
w 16 256 64 256 0
g 16 352 16 368 0
v 64 64 112 64 0 0 40.0 2.5 0.0 0.0 0.5
w 112 128 144 128 0
w 64 128 16 128 0
w 16 128 16 256 0
v 64 256 128 256 0 2 1000.0 1.65 1.65 0.0 0.5
a 336 144 464 144 1 3.3 0.0
w 336 160 336 192 0
w 464 192 464 144 0
w 464 144 512 144 0
r 592 144 592 256 0 1000.0
g 592 352 592 368 0
w 512 144 592 144 0
w 336 192 352 192 0
w 432 192 464 192 0
v 64 128 112 128 0 1 1.0 1.25 1.25 0.0 0.5
w 16 256 16 288 0
w 16 288 16 352 0
w 592 256 592 352 0
g 272 352 272 368 0
w 272 128 336 128 0
w 176 256 176 144 0
r 272 224 272 288 0 1000.0
w 272 128 272 224 0
w 272 288 272 352 0
159 144 128 208 128 0
r 208 128 256 128 0 1000.0
w 256 128 272 128 0
w 144 256 176 256 0
r 336 224 336 288 0 1000.0
g 336 352 336 368 0
w 336 288 336 352 0
w 336 192 336 224 0
r 352 192 432 192 0 1000.0
o 4 64 0 34 2.5 7.8125E-4 0 -1
o 0 64 0 35 5.0 9.765625E-5 1 -1
o 11 64 0 34 2.5 0.0015625 2 -1


Components Inside Circuit

DAC chip

clk chip

analog switch

Part No. Operating Voltage Min Volt Max Volt Frequency response Propagation delay Min Temp Max Temp Pin Price(U.S.)
SN74LVC1G66YZPR 1.65V~5.5V -0.5V 6.5V 175MHz(3V) >300MHz(3V) (*1) 0.8ns(3.3V) -40oC 85oC 6-pin 1:$0.48 100:$0.27
SN74AHC4066DR 2V~5V -0.5V 7V 30MHz(3V) 0.8ns(3.3V) -40oC 85oC 14-pin 1:$0.55 100:$0.33

(*1) different value of the RC circuit. ref. to the datasheet

more information about the series 74 in wiki: http://en.wikipedia.org/wiki/7400_series

op-amp buffer

  • OPA340


Possibly Useful References

An open source waveform generator