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  1. // Copyright 2013 Olivier Gillet.
  2. //
  3. // Author: Olivier Gillet (ol.gillet@gmail.com)
  4. //
  5. // Permission is hereby granted, free of charge, to any person obtaining a copy
  6. // of this software and associated documentation files (the "Software"), to deal
  7. // in the Software without restriction, including without limitation the rights
  8. // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  9. // copies of the Software, and to permit persons to whom the Software is
  10. // furnished to do so, subject to the following conditions:
  11. //
  12. // The above copyright notice and this permission notice shall be included in
  13. // all copies or substantial portions of the Software.
  14. //
  15. // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16. // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17. // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18. // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19. // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20. // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21. // THE SOFTWARE.
  22. //
  23. // See http://creativecommons.org/licenses/MIT/ for more information.
  24. //
  25. // -----------------------------------------------------------------------------
  26. //
  27. // Value to output on the DAC to get unitary gain.
  28. #ifndef STREAMS_GAIN_H_
  29. #define STREAMS_GAIN_H_
  30. namespace streams {
  31. // The DAC sends up to 2.5V through 25k = 0.1mA over the range of the DAC.
  32. // The offness compensation resistor sends -10V through 10M = 0.001mA.
  33. // Assuming the op-amp offset is negligible, the two balance for a DAC code of
  34. // 65536 / 100.0
  35. const int32_t kDefaultOffset = 655;
  36. // DAC code giving a unitary gain.
  37. const int32_t kUnityGain = 32767;
  38. // Slightly above unitary gain.
  39. const int32_t kAboveUnityGain = 32896;
  40. // Maximum gain in dB in lin mode with a DAC code of 65535 (6 dB).
  41. const int32_t kMaxLinearGain = 65536;
  42. // Maximum gain in dB in lin mode with a DAC code of 65535 (18 dB).
  43. const int32_t kMaxExponentialGain = 218453;
  44. const uint16_t kSchmittTriggerThreshold = 32768 * 5 * 2 / 3 / 8;
  45. } // namespace streams
  46. #endif // STREAMS_GAIN_H_