Changes between Version 5 and Version 6 of WikiStart

Timestamp:

Mar 17, 2017, 10:47:49 AM (8 years ago)

Author:

bouyer

Comment:

--

WikiStart

@@ -13 +13 @@
 We came up with the schematic at [[https://www-soc.lip6.fr/trac/soc-conso/export/1/hardware/pic_conso.sch.pdf]]. Hardware and software sources are available in the source section of the wiki, or via svn at https://www-soc.lip6.fr/svn/soc-conso/.
 
-A 1.350V precision diode is used as a voltage reference for the ADC. The input voltage is feed to ADC input 0 (AN0) via a voltage diviser. To cover the input range with enough accuracy 3 different values can be selected with a jumper.
+A 1.235V precision diode is used as a voltage reference for the ADC. The input voltage is feed to ADC input 0 (AN0) via a voltage diviser. To cover the input range with enough accuracy 3 different values can be selected with a jumper.
 
 3 Shut resistors are used for current measurements, selectable with a jumper. An amplifier will multiply the shut's voltage before feeding it to AN1.
@@ -28 +28 @@
 
 For voltage input, we selectable 3 divider values: 4.92, 11 and 19.33,
-which gives ranges of 6.63V, 13.5 and 26.1V respectively.
+which gives ranges of 6.07V, 12.35V and 23.88V respectively.
 
 For current input, we have 3 selectable shuts: 0.05, 0.1 and 0.2 ohms.
 The shunt's volatge is then amplified by 10 by the AD623 amplifier.
-This gives ranges of 2.68A, 1.34A and 0.67A respectively.
+This gives ranges of 2.45A, 1.23A and 0.61A respectively.
 
 For each tension or current range, we take 8 samples between 0 and a value
@@ -39 +39 @@
 
 From this process, we found that that the AD623 output can't go down to 0,
-it stays positive by anout 6mV.
-This means we can't measure currents smaller than 3mA on the 0.67A scale,
-and 12mA on the 2.68A scale.
+it stays positive by anout 5.5mV.
+This means we can't measure currents smaller than 2.75mA on the 0.61A scale,
+and 11mA on the 2.45A scale.
 We also find that, assuming an ideal power supply without noise or ripple,
 we have a +/-7 unit error on the ADC's output. This is less than 0.18% of the
-full range (or +/- 4.8mA on the 2.68A range input).
-
-
-
+full range (or +/- 4.4mA on the 2.45A range input).