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• #2288 olli tag

  Új Válasz 2013-12-21 17:48:20 #2288

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  olli

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  VB6-ban írt pcthermometer programmal kapcsolatban felmerült:
  8 db DS 1624 szenzort lehet címezni, egy további ADS 7828E 8 csatornás konvertert kellene I2C vonalon csatlakoztatni.
  Az ADC címe megegyezik a szenzorok egyikével, &H48, a csatorna kiválasztását hogyan kell beszúrni,
  Csatorna címe pl &H21, &H23, &H24
  "The address byte is the first byte received following the
  START condition from the master device. The first five bits
  (MSBs) of the slave address are factory pre-set to 10010.
  The next two bits of the address byte are the device select
  bits, A1 and A0. Input pins (A1-A0) on the ADS7828 determine
  these two bits of the device address for a particular
  ADS7828. A maximum of four devices with the same pre-set
  code can therefore be connected on the same bus at one
  time.
  The A1-A0 Address Inputs can be connected to VDD or digital
  ground. The device address is set by the state of these pins
  upon power-up of the ADS7828.
  The last bit of the address byte (R/W) defines the operation
  to be performed. When set to a ‘1’ a read operation is
  selected; when set to a ‘0’ a write operation is selected.
  Following the START condition the ADS7828 monitors the
  SDA bus, checking the device type identifier being transmitted.
  Upon receiving the 10010 code, the appropriate device
  select bits, and the R/W bit, the slave device outputs an
  acknowledge signal on the SDA line.

  The ADS7828 operating mode is determined by a command
  byte which is illustrated above.
  SD: Single-Ended/Differential Inputs
  0: Differential Inputs
  1: Single-Ended Inputs
  C2 - C0: Channel Selections
  PD1 - 0: Power-Down Selection
  X: Unused
  See Table I for a power-down selection summary.
  See Table II for a channel selection control summary.
  MSB 6 5 4 3 2 1 LSB
  1 0 0 1 0 A1 A0 R/W
  PD1 PD0 DESCRIPTION
  0 0 Power Down Between A/D Converter Conversions
  0 1 Internal Reference OFF and A/D Converter ON
  1 0 Internal Reference ON and A/D Converter OFF
  1 1 Internal Reference ON and A/D Converter ON

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