added "desired_freq_2_sfp_ch""function according to SFF8690 (see Table 4-3)

11b608c2 · Peter Jansweijer · 9af53fe5 · 11b608c2
Commit 11b608c2 authored Sep 06, 2019 by Peter Jansweijer
Hide whitespace changes
Inline Side-by-side

Showing with 21 additions and 0 deletions

itu_conversions.py sw/lib/itu_conversions.py +21 -0

No files found.
--- a/sw/lib/itu_conversions.py
+++ b/sw/lib/itu_conversions.py
@@ -51,3 +51,24 @@ def wavelength_2_itu(wavelength):
  itu_channel = round(itu_channel,1) # round to 1 decimal

  return(itu_channel)
+
+############################################################################
+def desired_freq_2_sfp_ch(desired_freq, first_freq, grid):
+  """
+  converts desired frequency into SFP channel number
+  input:
+  desired_freq  <int> The desired freqency in Hz
+  first_freq    <int> Lasers First Frequency in Hz
+                      Following SFF8690 Table 4-3 the Lasers First Frequency
+                      can be read from I2C 0xA2 page 2 Addr 132-135.
+  grid         	<int> Laser's minimum supported grid spacing in Hz
+                      Following SFF8690 Table 4-3 the Lasers First Frequency
+                      can be read from I2C 0xA2 page 2 Addr 140-141.
+
+  return:
+  sfp_ch        <int> The number to set in the tunable SFP to obtain the
+                      desired frequency, according the the equation given
+                      in SFF8690
+  """
+  
+  return(int(1+(desired_freq - first_freq) / grid))