Drink Mixer

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Drink Mixer (Audio Mixer)

The Drink Mixer is a 6-8 Channel Audio Mixer with a peripheral interface operated by the Tin Can Tools Hammer. This was a Senior Design Project presented for Purdue University's Senior Design Class ECE 477. In order to pass this class at least 3 of 5 project success criteria must be completed.

Project Success Criteria:

  • 1. An ability to mix and adjust levels of 6-8 Channels of Audio
  • 2. An ability to change individual equalizer settings for each channel.
  • 3. An ability to display settings/ channel information on an LCD Display.
  • 4. An ability to save and load scene settings (moving faders)
  • 5. An ability to display the amplitude of an audio output signal.

Of the above project success criteria, currently 2,3, and 4 are completed with the help of the Hammer ARM920T Chip.

More information and pictures will be added to this later but for now a link to the Purdue University Senior Design Project Page for this project can be found below.

Purdue ECE477 Team 2 Project Page


The Hammer is not capable of processing audio at rates necessary for this project with all of the floating point calculations involved. As a result several processors were used

 1  - ADSP-21262 SHARC DSP

The ATMEGA32A were used as peripheral processors that kept track of motorized faders as well as Rotary Pulse Generators (RPGS) and LED Bar graphs. These processors were all placed on an i2c bus and monitored and updated several times / second by the Hammer S3C2410A ARM920T Processor.

The information acquired by the Hammer from the various peripherals as well as the user interface are then sent to a SHARC ADSP-21262 over an SPI bus. This information is processed and audio levels are adjusted accordingly. (Currently the audio portion of the project is incomplete as too much crosstalk is occurring on the A/D Data line).

Power Requirements

Power Rails +-15V @ 320 mA each direction
+9 V @ 8.8 A
+5 V @ 1224 mA
+3.3 V @ 2.5 A
(NOT a power rail, but must be considered...)
+1.3V @ 160 mA for DSP

Total Power Consumption 3.84 Watts + 20% = 4.6 Watts Needed in positive 12VDC
3.84 Watts + 20% = 4.6 Watts Needed in negative 12VDC
This is 383 mA @ 12 Vdc

88 Watts + 20% = 105.6 Watts Needed in positive 10VDC (using switching power supply)
This is 10.56 A @ 9 Vdc

6.12 + 8.25 + 0.352 + extra = 14.722 Watts + 20% = 17.66 Watts Needed in positive 5VDC (linear, then step-down converted to lower voltages)
This is 3.53 A @ 5 Vdc

LCD Display (Panasonic EDMGRB8KJF) 1.5 AMP 3.3V Max

JFET Preamplifier 40mA x 8 = 320 mA @ +-15V (in each direction)

Motorized K-Faders 800 mA x 11 = 8.8 A @ 9V

Hammer Arm9 5VDC @ 120 mA (typical), 300 mA (max)

Atmel (ATMEGA32A) Vcc = 5Vdc, Active @ 8MHz: Max = 15 mA
Vcc = 5Vdc, Active @ 16MHz: Max(estimated)< 40 mA each

Therefore, total = 9 x 40mA = 360 mA @ 5Vdc

SHARC (Analog Devices ADSP-21262) External (I/O) Supply Voltage (VDDEXT) 3.13 to 3.47 V (optimally 3.3 VDC) @ 1A
Requires low voltage (approx. 1.3V for something else)

LED Bar Graph 2 mA per LED x 10 = 20 mA per graph x 8 = 160 mA @ 2.2 V (just for current draw, voltage rail will be done on channel PCB)

LED Level Display 5 mA per LED x 40 = 200 mA @ 5V

Audio ADC (AD1871 x4) 5Vdc @ 45mA each = 180mA @ 5Vdc

Audio DAC (AD1833A) 5Vdc @ 46mA each = 184mA @ 5Vdc


This is a picture of the hammer running on the main board.
This is an inside view of the DrinkMixer (Audio Mixer Board). It's getting to be quite a lot of wires. This is mainly due to our PCB restriction of a maximum of 60 square inches per PCB.

Useful Resources

Throughout the development cycle of this project many resources were utilized from this site as well as improved upon and/or updated.