Stellarcore
New Member
I recently saw a cool project that a company is making: https://www.becausewecan.org/LED_Coffee_Table_The_Wave
I'm moving out next week and will be needing a coffee table, so I thought it might be cool to make something like the table in the link.
I've been planning a bit and think I can do a decent job. Unlike the table in the link, I dont think its neccessary to make a huge PCB the size of the entire table (must cost them a fortune!). Instead, I'm opting for several smaller pcb's (that I can make in the free version of eagle) with flexible conduit that runs the LEDs and phototransistors under the table.
My project would be controlled digitally by a PIC. I've got a bunch of I2C 16 bit I/O expanders from Microchip that I'd like to use. My design would split the entire project into 8 PCBs, one master board (with the PIC and power circuitry etc..) and 7 slave boards. Each slave board would be identical to the master except certain parts will not be populated. Each board will have five 16 bit I/O expanders. Four I/O expanders will control four rows of LEDs and two rows of phototransistors would be polled by the fifth I/O expander.
Because I can only put eight I/O expanders on a single I2C bus, I will run need nine I2C busses between the boards, as well as power, ground, and a PWM signal that will be used to control the brightness of all the LEDs. All 8 of the phototransistor expanders will be on one bus, and the the LED expanders will share a bus between two boards. Each slave board would have some jumpers on it so that they can be addressed differently.
Because my project would have up to 512 white LEDs rated at 25mA each, I've been trying to think of a way to supply enough current that I can turn all the LEDs on at a time if I wish (the advantage of it being digitally controlled will be that I could use the whole thing as a giant sign board if I wanted or play neat animations, etc...). The total current needed (plus any current dissipated by the buttloads of switching FETs that I'll need) seems to be around 512*25ma = 12.8 Amps @ 5 Volts.
Does anyobdy have any idea what I could use to provide that much current that would be relatively quiet? Also, what gauge of wire do I need to run that much current between the boards? How big should my power traces be?
I'm moving out next week and will be needing a coffee table, so I thought it might be cool to make something like the table in the link.
I've been planning a bit and think I can do a decent job. Unlike the table in the link, I dont think its neccessary to make a huge PCB the size of the entire table (must cost them a fortune!). Instead, I'm opting for several smaller pcb's (that I can make in the free version of eagle) with flexible conduit that runs the LEDs and phototransistors under the table.
My project would be controlled digitally by a PIC. I've got a bunch of I2C 16 bit I/O expanders from Microchip that I'd like to use. My design would split the entire project into 8 PCBs, one master board (with the PIC and power circuitry etc..) and 7 slave boards. Each slave board would be identical to the master except certain parts will not be populated. Each board will have five 16 bit I/O expanders. Four I/O expanders will control four rows of LEDs and two rows of phototransistors would be polled by the fifth I/O expander.
Because I can only put eight I/O expanders on a single I2C bus, I will run need nine I2C busses between the boards, as well as power, ground, and a PWM signal that will be used to control the brightness of all the LEDs. All 8 of the phototransistor expanders will be on one bus, and the the LED expanders will share a bus between two boards. Each slave board would have some jumpers on it so that they can be addressed differently.
Because my project would have up to 512 white LEDs rated at 25mA each, I've been trying to think of a way to supply enough current that I can turn all the LEDs on at a time if I wish (the advantage of it being digitally controlled will be that I could use the whole thing as a giant sign board if I wanted or play neat animations, etc...). The total current needed (plus any current dissipated by the buttloads of switching FETs that I'll need) seems to be around 512*25ma = 12.8 Amps @ 5 Volts.
Does anyobdy have any idea what I could use to provide that much current that would be relatively quiet? Also, what gauge of wire do I need to run that much current between the boards? How big should my power traces be?