MP3 Player – From Scratch

For the final project for an embedded systems class, we used Cadence to make a full MP3 player from start to finish including Bill of Materials, schematic, PCB layout, and even Gerber Files–everything up until the unit could be produced at a fab house. This was a fun project that exposed all the nitty-gritty details of Cadence and design work.

The Assignment was to design an MP3 player based on the VS1011E-L MP3 decoder ASIC and an Atmel ATmega2561-series microcontroller with Compact Flash (CF) storage with:

1) A full schematic of all components necessary for the design in Cadence Allegro’s
Design Entry CIS
2) A 4-layer PCB layout for the above schematic, which must be synchronized with
part 1 (that is there must be a 1:1 correlation between connections and
components on the PCB and nets and components on the schematic that is
3) Gerber files — necessary for fabricating the PCB
4) A Bill of Materials (BOM) for your PCB, including vendor part number and
pricing information.

Required Components:
– Processor: ATmega2561 series
– MP3 Decoder: VS1011E-L
– OLED Graphics Display 128×128, SSD1339 Driver
– Connector for above OLED: Omron XF2M-3015-1A
– Compact Flash Socket: AVX 315620050116871+
– Headphone Jack: CUI CP-3524SJCT
– Navigation Switch: On Shine Enterprise OS-1305 (from Spark Fun Electronics)
– All Crystals: Abracon ABM8 series if available, otherwise physically smallest
– All Resistors, Capacitors, Inductors: 0603 package if possible

The Microprocessor was clocked at the maximum frequency possible. Surface mounts components were used whenever possible. For resistors, capacitors, and similar discrete devices, attempt to use 0603 packages if the part is available in that size; otherwise use the smallest package you can find.

The linear voltage regulator was chosen by assuming a +6VDC supply to step down to 3.3v. No power switches were necessary. The OLED display could be connected either via an 8-bit data bus OR via SPI. Many of the parts did not have their own footprints and we had to make our own. No firmware was required for this project, just the hardware design.

Board Tolerances and Specifications
4-layer PCB, consisting of top and bottom plus Ground and Power layers
Minimum trace space and width: 8mil
Minimum annular ring: +10mil diameter for vias, +14mil diameter for components
Minimum via drill size: 10mil diameter
Minimum component drill size: 15mil diameter
Soldermask swell: 5mil over total width/height/diameter
Copper to board edge: 20mil minimum

Design Process Decisions:

– According to the datasheet, the processor can only run at 8 MHz if powered at 3.3 volts. The faster 16 MHz mode requires at least 4.5 volts.
– An ISP connector was included for quick programming during firmware development.
– The RESET switch was pulled externally high to ensure a proper reset regardless of CPU settings. A reset switch was not included because the same result can be achieved using the programming during firmware development and by power cycling during normal operation.
– The navigation switch was split between Port G and Port D to allow contiguous pins to be use for the three pins.
– The navigation switch is connected without external pull-ups. Therefore, the microcontroller must enable internal pull-ups for proper operation.
– The AREF pin was left unconnected because the firmware is not going to perform any A2D operations.
– Port E was chosen for the LED screen because the pins are oriented in the correct direction such that the bus does not need to be twisted.
– The LED uses a parallel interface such that the SPI port can be dedicated to the MP3 decoder.
– The LED is hardwired to use the 6800-series interface, which is similar to the LCD code from the 292c development board. Therefore, our firmware can be adapted from our existing code. This is another reason to use a parallel interface consider that 292c LCD code also uses a parallel interface.
– The LED design wraps the ribbon cable around the back of the board. This allows to reduce the space required by the design.
– The MP3 interface is taken directly from the MP3’s datasheet for typical circuit interface.
– The LT1109CZ-12 was chosen because the 12 volt does not have a very high current requirement (<5 mA), and it does not require a very large number of external components (one inductor, one capacitor and one diode)
– The ADP3333 was chosen because it has very good stability without requiring large capacitors. It will be okay with 1.0uF small surface mounted capacitors. Furthermore, it has a very low dropout. It can only supply 300 mA which means certain high-speed Compact Flash will not work with our design, therefore, we will restrict the CF cards used.

Bill of Materials:
Name Designator Vendor P/N Qty Unit Price USD

ATmega2561 IC1 Digi-Key ATMEGA2561-16AU-ND 1 16.99 16.99
Resistor 10k R14 Digi-Key CRCW060310KJNEA 5 0.04 0.20
8 MHz Crystal Y1 Digi-Key 535-9164-1-ND 1 0.88 0.88
Cap 18pF C10, C11 Digi-Key BC1228DKR-ND 2 0.03 0.06
Cap 100nF C31, C32, C34 Digi-Key 399-1099-6-ND 3 0.03 0.09
ISP Header J8 Digi-Key A26569-ND 1 2.16 2.16
Nav Switch J7 SparkFun OS-1305 1 1.95 1.95
Sub Total 22.33

OLED SSD1339 128x128 SparkFun LCD-00712 1 36.95 36.95
XF2M-0305 Omron SparkFun LCD-00732 1 2.95 2.95
3.6v Zener D1 DigiKey 1N5334BG-ND 1 0.12 0.12
Resistor 51 R18 Digi-Key CRCW060351JNEA 1 0.04 0.04
Resistor 100 R40, R41 Digi-Key CRCW0603100JNEA 2 0.04 0.08
Cap 10uF C39, C40, C41, C44, C16 Digi-Key PCC2395DKR-ND 5 0.36 1.80
Cap 1uF C12, C13, C14, C15 Digi-Key 399-5090-6-ND 4 0.08 0.32
Sub Total 42.26

MP3 Decoder IC Digi-Key COM-08126 1 19.95 19.95
CUI CP-3524SJCT CP-3524SJCT-ND 1 0.90 0.90
Resistor 100K R27, 22-25 Digi-Key 541-100KGDKR-ND 5 0.04 0.20
Resistor 1M R26 Digi-Key 541-1MGDKR-ND 1 0.04 0.04
Resistor 1K R42-45 Digi-Key 541-1KGDKR-ND 4 0.04 0.16
12.288 MHz Crystal Y2 Digi-Key 300-8131-1-ND 1 1.10 1.10
Cap 33pF C22, C23 BC1231DKR-ND 2 0.03 0.06
Cap 100nF C28 Digi-Key 399-1099-6-ND 1 0.03 0.03
Cap 10nF C19-21 Digi-Key 720-1021-1-ND 3 0.39 1.17
Resistor 20 R19-21 Digi-Key 541-20GDKR-ND 3 0.04 0.12
Sub Total 23.73

Compact Flash
AVX 315620050116871+ AVX Corp. Digi-key 478-4068-ND 1 6.53 6.53
Resistor 51K R28-39 Digi-Key 541-50KGDKR-ND 12 0.04 0.48

Sub Total 6.53

3.3V regulator U5 Digi-Key ADP3333ARM-3.3RL7-ND 1 1.07 1.07
12V DC-DC Boost U4 LT1109CZ-12-ND 1 1.90 1.90
Cap 1uF C37-38 Digi-Key 399-5090-6-ND 2 0.08 0.16
Cap 10uF 25V C18 Digi-Key PCE4194CT-ND 1 0.08 0.08
Diode Schottky (1N5818) D2 Digi-Key 1N5818-E3/1GI-ND 1 0.15 0.15
Inductor 22uH L1 445-3155-1-ND 1 0.22 0.22
Power Jack J3 Digi-Key CP1-021PJCT-ND
Sub Total 3.58
4-Layer PCB w/ Free Pizza Advanced Circuits Student 4-layer 1 66.00 66.00
Sub Total 66.00

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