Required Kicad Hardware library: https://github.com/cracked-machine/KicadLibrary
For the corresponding SW repository: MidiLedController_sw
Power Supply: 12V @ 2A (center positive). Total quiescent current consumption: 85mA Voltage output per channel: 10V Current output per channel (Nom.): Total current consumption (Nom.): Current output per channel (fault limit): Total current consumption (fault limit): 2A
A 12V DC input supply is stepped-down to 10V. Most of this will be used to power the LEDs. This is regulated down to provide 5V @ 100mA for the status leds. Additionally 3.3V @ 20mA is provided to the microcontroller.
MIDI Note-On commands are received and synchronised with the gating of 9 independant LED output channels. The brightness of all 9 channels can be adjusted simultaneously at the rear of the module.
Fault protection monitors each output channel for short-circuit and over-current conditions. Fault protection is done on the high side of the switch. MIDI data transmission is done on the low side of the switch. i.e. the output channel anode remains at 5V (during normal operation) while the cathode is toggled by the Microcontroller GPIO.
Individual output channel status is indicated with a tricolour LED. See details on the Status LED sub-system below.
Each output channel has a tricolour LED. As before a green LED indicates that a load is connected to the output channel and power delivery to that channel is functioning as normal. An overcurrent or short circuit event is indicated by a red LED and all power is disabled from that output channel.
A blue LED indicates that no load is connected to the output channel. At this point, if MIDI data is still being transferred to that channel, the status LED will alternate between green and blue, in sync with the received MIDI data. This allows testing of the MIDI data transmission without needing to connect a load to the output channel.
When the load is connected, the status LED will always remain solid green.
A red power fault status such as over current or short circuit will always override the other status colours.
- upgrade SMPS to drop-in 3A components (TP56339, TPS54302, TPS54309). Considerations are Fsw/L1 size, Thermal Limits and cooling.
- Upgrade output series SOT23 transistor to higher currrent/thermal limit component...or to larger component (SOT223?)
- Test audio input triggering
- Additional pot control for reset delay (dual gang/ concetric pot)
- Upgrade DIP4 to DIP6