Differences

This shows you the differences between two versions of the page.

--- vfd_driver [2016/02/01 14:55] – [micro-controller] kingkevin
+++ vfd_driver [2016/02/02 13:16] – [micro-controller] kingkevin
@@ Line 75: / Line 75: @@
   - #LE: enable latch on low (aka. negative LE, or NLE)
   - STR: strobe the shifted data
-  - NC: not connected
+  - AUX: connected to ground when the auxiliary display is present
 {{  :vfd_driver:cn1_jumper.jpg?200|CN1 short}}
@@ Line 81: / Line 81: @@
 The second VFD has 10 digits, and is a copy of the 10 digits from the main VFD (minus comma and underline).
-If you don't have the auxiliary VFD connected, the main VFD will not light up.
+The AUX pin of CN2 is shorted to ground when the auxiliary VFD is connected.
-To circumvent this protection just short the 3rd right-most to pin with the 2nd right-most bottom pin.
+You can use the AUX pin to detect if the auxiliary VFD is present by pulling the pin up and checking if it's low (because shorted to ground).
+You can also the use AUX pin as second ground pin (i.e. for the VPP power suply).
+If the auxiliary VFD is not present, just short the 3rd right-most top pin with the 2nd right-most bottom pin.
 ==== segments ====
@@ Line 195: / Line 197: @@
 | GPIO | PA4 | 6 | NLE |
 | GPIO | PA6 | 7 | STR |
-| | | 8 | NC |
+| | | 8 | AUX |
 The VPP and GND pins to drive the VFD segments are provided using an external power supply.
 I use a [[http://www.aliexpress.com/item/120W-DC-DC-Boost-Converter-10-32V-to-36-60V-48V-54V-4A-Step-Up-Adjustable/1414029224.html|boost converter]] and set it to 50V.