Difference between revisions of "Modulation Plugin"

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===[http://chungyan5.no-ip.org/vc/?root=modulation_plugin SVN SERVER]===
  
 
==Components Inside Circuit==
 
==Components Inside Circuit==

Revision as of 19:27, 24 November 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

Overall Performance

  • I2C Baudrate:
  • Output Voltage Range:
  • Output Frequency Range:
  • Number of channels:


Selected Chips

Part No. Description Order Chip Call Sample
DAC6574IDGS Quad-channel 10-bit I2C DAC Digikey No need
CY2545??? Quad PLL I2C Programmable Clock Generator HQEW Try Contact Cypress
DS1089L 3.3V Center Spread-Spectrum EconOscillator Digikey Maxim
MC74VHC4053DT Analog Multiplexers Try Contact ON Semiconductor

CY2545 is out of stock in digikey, so there is no more information about it.


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

SVN SERVER

Components Inside Circuit

DAC chip

  • Part No: DAC6574IDGS
  • datasheet
  • Resolution: 10-bit
  • I2C clock Frequency: upto 3.4Mbps
  • No of channels: 4
  • Operating Voltage: 2.7 - 5.5V
  • Temperature range: -40 - 105oC


Clock Generator chip

  • CY2545???
  • datasheet
  • buy at here
  • I2C clock Frequency: upto 400kbps
  • No of channels: 4
  • Operating Voltage: 2.5V, 3.0V, 3.3V
  • Temperature range: -40 - 85oC
Comparison between Different Clock Generator Chips
Part No. Opertating Volt Operating Freq Min Volt Max Volt output freq Min Temp Max Temp Pin
CY2545 2.5V, 3.0V, 3.3V 400KHz -0.5V 4.5V 3- 166 MHz -40oC 85oC 24-pin
DS1089L 3.3V 400KHz 2.7V 3.6V 130kHz - 66.6MHz -40oC 85oC 8-pin 
CLK 1-8 : frequency output
  CLK 3 : frequency selection (FS)
          (Function 2) cy2545 has 4 PLLs, each PLLs can be set 2 frequency, CLK 3 use to select the frequency
  CLK 6 : spread spectrum ON/OFF control input
          (Function 2) for synthesizing and modulating the frequency
Vdd_CLK_BX (X=1,2,3) control the output frquency of Blanck X (X=1,2,3) 

               +------------------+        
               |         |        |------CLK 1
               |         | Bank 1 |
               |         |        |------CLK 2
               |------------------|     
               |         |        |------CLK 3
               |         | Bank 2 |------CLK 4
               |         |        |------CLK 5
               |------------------|
               |         |        |------CLK 6
               |         | Bank 3 |------CLK 7
               |         |        |------CLK 8
               +------------------+
CLKIN/RST ---1. 2.5V/3.0V/3.3V external reference clock frequency
             2. Reset function POR :back to default condition / 
                       Clean Start : keep the programmed value
Xout        Crystal frequency output
Xin/EXCLKIN Crystal frequency input/ 1.8V external clock input
  • Coding
 [Start Bit]->[7-bits devices]-->[R/W bit]-->[  Slave  ]-->[   8-bits     ]--> ..   
 [ address ]  [   address    ]   [       ]   [ CLK ACK ]   [memory address]   
 
 ..[ACK]-->[8-bits]-->[  8-bits    ]-->....[  8-bits    ]......until... [stop bit]
   [   ]   [ data ]   [data in MA+1]       [data in MA+n]               [        ]


Analog Switch

  • Part No: MC74VHC4053
  • datasheet
  • Switching Frequency: 120MHz
  • No of channels: 4
  • Operating Voltage:
  • Temperature range: -40 - 85oC
Comparison between Different Analog Switches
Part No. Operating Volt(V) Freq Resp(Hz) at 3V On-state Resist(Ω) at 3V Min Volt(V) Max Volt(V) Min Temp Max Temp Indenpent Circuit Voltage Supply Source Pin
SN74AHC4066 Vcc : 2V~5.5V 35MHz 29Ω Vcc : -0.5V Vcc : 7V -40oC 85oC 4 single 14
74HC4051D Vcc : 2V~10V Vee : -10V~2V Nil 80Ω Vcc :-0.5V Vee : -11V Vcc : 11V Vee : 2V -40oC 85oC 4 Dual 16
MC74VHC4051 Vcc : 2V~6V Vee : -6V~0V 80MHz 80Ω Vcc :-0.5V Vee :-7V Vcc : 7V Vee : 5V -40oC 85oC 4 Dual 16
MC74VHC4052 Vcc : 2V~6V Vee : -6V~0V 90MHz 90Ω Vcc :-0.5V Vee :-7V Vcc : 7V Vee : 5V -40oC 85oC 4 Dual 16
MC74VHC4053 Vcc : 2V~6V Vee : -6V~0V 120MHz 90Ω Vcc :-0.5V Vee :-7V Vcc : 7V Vee : 5V -40oC 85oC 4 Dual 16
  • more information about the series 7400 in wiki: http://en.wikipedia.org/wiki/7400_series
  • there is model G which is super high speeds at more than 1 GHz in 7400 family, however this model is very expensive.


op-amp buffer

  • OPA340


Possibly Useful References

An open source waveform generator

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