In SX Microcontrollers, SX/B Compiler and SX-Key Tool, tdg8934 wrote: Bean, Thank you for the RC circuit idea. That's right the resistor was inline. That seemed to help but I think there is a much deeper issue with power from 5vdc and 12vdc over these 44 boards. Currently there is (1) 5vdc 50A supply with (2) connections being run into boards (1) and (40) of the 43 total. There is also (2) 12vdc 16.6A supplies with (3) connections for each supply run into boards (1), (8), (16), (24), (31) and (38). Looking at the attached spreadsheet you will see in bold where the power supplies are attached and what the strange voltage readings are. When the SX48 sends data through the cascaded 74HC595 / uln2803 modules and all the LEDs are lit up (except for 1 LED that is sequencing through the 352 LEDs as being in an off state), the voltages drop significantly. I haven't checked the voltages in the reverse condition (1 LED "on" sequencing through 352 LEDs) either. Could this be a power issue? Each module has optional connections and jumpers to accept 5vdc and 12vdc instead of running them via the RJ45 cable from board to board. Currently the power supplies tap into the above mentioned connections and only use the RJ45 cable run for power between each power connection of either 5vdc or 12vdc as appropriate. When a single LED is sequencing through the 352 LEDs, it works correctly. When inverting the SHIFTOUT statement with a ~, (e.g. all LEDs are one and only 1 is off while sequencing), the voltages are wacked out of place and it works except until the last few lights where double LEDs are off while sequencing and it skips and jumps over some of the LEDs. Anything I can try here? Thank you. ---------- End of Message ---------- You can view the post on-line at: http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=453400#m453785 Need assistance? Send an email to the Forum Administrator at sysadmin@parallax.com The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2010 (http://www.dotNetBB.com)