This project is still in progress, plenty more to come.
The original design of the blinker circuit to be implemented in the next generation Solar Car (SpitFire) for McMaster University.
Its simple architecture is ideal for teaching entry-level students. However, this design is not very practical considering its low-efficiency methods and utilization of 16 N-channel mosfets for driving the LEDs.
Breadboard prototyping the circuit.
Playing around with it's capabilities.
The circuit configuration of the LED strings.
The prototyping design for the String of LED on a PCB.
Front side of the PCB.
Back side of the PCB.
The boards have just in from OSH park!
Gold plated solder pads.
The new, higher efficiency blinker circuit which contains many new features!
The 16F883 PIC Micro-controller, gathering both inputs from the toggle SPDT switches, SPI output for the LED drivers, ICSP (In-Circuit Serial Programming) for programming the MCU while it's on the PCB and Op-Amp inputs for frequency filtering and advanced Digital Signal processing.
Compared to the older design, which used a regulator to supply 5V out to the MCU, this new circuit contains a Texas Instrument Step-down Switch mode power supply. This integrated system has an efficiency of roughly 95% at 5V out, and a maximum current of 2.25 amps.
For increased performance and efficiency, I used the Texas Instrument TLC series SMD constant-current drivers to control the super flux led strings. These three components are current set by an external resistor on one of the pins, and can drive up to 16 channels at 120 mA each. They are controlled by the 16F883 using the Serial Peripheral Interface. Another neat feature of this driver is that instead of the standard 4-pin SPI requirement (SDI, SDO, SS, CLK), it has a fifth communication pin (~OE) inverted Output Enable. This pin simplifies the application of PWM for controlling the brightness of each slave.
Compared to the older design, this new configuration allows only the correct amount of threshold voltage to exit each channel to turn on the LEDs, while the older configuration had a constant 12 V out, roughly 3 V drop on the LED and the remaining 9 V was burned off through power resistors. Not very efficient especially when this circuit is designed to be implemented into a solar car.
Compared to the older design, this new configuration allows only the correct amount of threshold voltage to exit each channel to turn on the LEDs, while the older configuration had a constant 12 V out, roughly 3 V drop on the LED and the remaining 9 V was burned off through power resistors. Not very efficient especially when this circuit is designed to be implemented into a solar car.
The frequency filter hardware before going into the analog input pins of the MCU for DSP. Three filtering levels are used to extract information from the audio input before being passed on to the MCU. The information is then used to determine the brightness and control of each Red, Green, and Blue light in real-time. This will create a light show which will react directly to the music being played.
The top op-amp has a Sallen-Key Low-pass filter configuration and a cut-off frequency of 480 Hz, this will only allow low frequency signals of music/audio to pass through and to be measured by the MCU. The next two op-amps use a Multiple-Feedback band pass configuration and both have a different center frequency, 1500 Hz is used for the medium range filtering and 4500 Hz for High frequency audio. The lower and upper bound cut-off of these center frequencies can be adjusted by software using basic DSP techniques. The bottom-most Op-amp is used as an amplifier since most signals coming directly from the audio jack are roughly 0.1 to 1 V depending on the amplitude, this step-up configuration amplifies it by 1 + R1/R2 giving me a wide range of gain selection.
The top op-amp has a Sallen-Key Low-pass filter configuration and a cut-off frequency of 480 Hz, this will only allow low frequency signals of music/audio to pass through and to be measured by the MCU. The next two op-amps use a Multiple-Feedback band pass configuration and both have a different center frequency, 1500 Hz is used for the medium range filtering and 4500 Hz for High frequency audio. The lower and upper bound cut-off of these center frequencies can be adjusted by software using basic DSP techniques. The bottom-most Op-amp is used as an amplifier since most signals coming directly from the audio jack are roughly 0.1 to 1 V depending on the amplitude, this step-up configuration amplifies it by 1 + R1/R2 giving me a wide range of gain selection.
Prototyped a working SPI with two constant current drivers, and implemented the filter system.
Top side.
Bottom side.
Programming the pic16f883 using a pickit2 clone.
This version corrects some of the errors noticed in the previous version (flipped 12V and gnd, wrong CAN bus connections, no status LEDs, molex connectors too big, unlabelled power connections). This new design also has a more compact arrangement, resulting in a lower cost for prototyping.
