mikroElektronika BassBoy User Manual

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assBoyB

Monophonic digital MIDI controlled bass synthesizer

Manual

MIDI Device

CREATED BY: Aleksandar Krsti @ć

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BassBoy

BassBoy is a monophonic digital MIDI controlled bass synthesizer. Device receives all information via MIDI input ( connector). Sampling frequency is 31.25KHz which generates audio range up to 15.625Khz. Although it's based on 8-bit processor, the signal processing inside the unit is 16-bit. The unit consists of oscillator which generates SAW & SQUARE WAVE using 16-bit band-limited wavetables, thus making the number of harmonics limited. After that, the signal itself goes through a simple implementation of MOOG filter, whose frequency range is chosen by MIDI commands and which is affected by the level of the envelope. The filtered signal then comes to the controlled amplifier, which creates the signal shape, and in the end throughDAC (WM8762) and pre-amp circuit goes to the audio jack 6.35mm. The unitis mono, and 6.35mm jackis also used as carrierfor the circuit board itself.

MIDI IN

It is crucial that the power supply unit connected to the BassBoy ( connector) is within specifications : +10V to +13V max. MIDI channel and the note interpretation mode (from now on, refered to as connector) must be chosen before turning on the unit. The location of the jumpers for choosing MIDI channel and the note interpretation mode is shown on the fig1-3.

CH&MODE

IMPORTANT!!!

BassBoy

MikroElektronika

technical support : andigo.office@gmail.com

Figure 1-1: BassBoy

Figure 1-2: Wiring diagram

Low Current LEDS or LEDS with mcd>200

AACC

POWERONMIDI

RECEIVE

POWER SUPPLY INPUT, DC +10V ... +13V max

MIDI INPUT DIN5 Female Connector Front View

Audio Output

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MIDI control

Selection of SAW or SQUAREwave is done viaProgram Change, where Program 1 is SAW wave andProgram 2 is SQUAREwave, then sequentially repeats SAW wave as Program 3, SQUARE wave as Program 4 and so on until Program 128. The unit has two ways of interpretation of received MIDI notes: SEQUENCER MODE and LIVE MODE. Interepretation mode is selected via jumper located on connector labeled as “CH&MODE”, while reproduced notes are within range from MIDI note 24 to MIDI note 72 (C1 – C5). The unit doesn't support MIDI pitch change control. Duration and level of envelope only affects the filter. In case that note has accent, then it also affects the controlled amplifier.

SEQUENCER MODE is mode in which the way of playing current note depends on the way the last note was played. The way of playing the note is defined by it's velocity, which is shown in this table:

Velocity 0 = NOTE OFF . It has the same meaning as a standard MIDI message $80 note $00. This defines end of duration of audibility (GATE) of the same note.

Velocity 1 - 16 = NOTE OFF. Note is being turnedoff, unless the previous note had a SLIDE function, in which case it lasts as long as the GATE of the samenote.

Velocity 17 - 32 = NOTE OFF + SLIDE. Similar to the previous case, but this time note stays on until the next note.

Velocity 33 - 48 = NOTE ON. Duration of the note is defined by the GATE. It turns the note on and triggers the envelope, but it is applied only if the previous note doesn't have SLIDE turned on ( portamento, gradual slide from previous note to current note). If the previous note had SLIDE turned on, then envelope wouldn't be triggered and only SLIDE effect would be executed. Duration of the envelope is defined by MIDI command CC 57.

Velocity 49 - 64 = NOTE ON + SLIDE. Duration of the note is until next note and is not defined by GATE. It turns the note on and triggers the envelope, but it is applied only if the previous note doesn't have the SLIDE turned on. If the previous note had the SLIDE turned on, then envelope wouldn't be triggered and only the SLIDE effect would be executed. Duration of the envelope is defined by MIDI command CC 57.

Velocity 65 - 80 = NOTE OFF + ACCENT. Same as NOTE OFF. Left for compatibility reasons.

Velocity 81 - 96 = NOTE OFF + ACCENT + SLIDE. Same as NOTE OFF + SLIDE. Left for compatibility reasons.

Velocity 97 – 112 = NOTE ON + ACCENT. Duration of the note is defined by the GATE. It turns the note on and triggers the envelope, but it is applied only if the previous note doesn't have SLIDE turned on. If the previous note had SLIDE turned on, then envelope wouldn't be triggered and only SLIDE effect would be executed. Duration of an envelope is a constant ~250mS. Value of the accent is added to the level value of the note. Accent is defined by the MIDI command CC 58.

Velocity 113 - 127 = NOTE ON + ACCENT +SLIDE. Duration of the note is until next note and is not defined by the GATE. It turns the note on and triggers the envelope, but it is applied only if the previous note doesn't have the SLIDE turned on. If the previous note had SLIDE turned on, then envelope wouldn't be triggered and only SLIDE effect would be executed.Duration of the envelope is a constant ~250mS. Value of the accent is added to the level value of the note. Accent is defined by the MIDI command CC 58.

BassBoy

MikroElektronika

technical support : andigo.office@gmail.com

Figure 1-3: CHANNEL & MODE JUMPER POSITION

LEGEND:

JUMPER

FREE

MIDI CH1

MIDI CH2

MIDI CH3

MIDI CH4

MIDI CH5

MIDI CH6

MIDI CH7

MIDI CH8

MIDI CH9

MIDI CH10

MIDI CH11

MIDI CH12

MIDI CH13

MIDI CH14

MIDI CH15

MIDI CH16

MIDI CH1

MIDI CH2

MIDI CH3

MIDI CH4

MIDI CH5

MIDI CH6

MIDI CH7

MIDI CH8

MIDI CH9

MIDI CH10

MIDI CH11

MIDI CH12

MIDI CH13

MIDI CH14

MIDI CH15

MIDI CH16

LIVE MODE with CHANNEL SELECTION

SEQ MODE with CHANNEL SELECTION

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LIVE MODE is amode in which the durationof the note is definedbythe GATE.VELOCITYdefines the way notes arebeing played:

Velocity0 – 100 = NOTEON.Triggersthe envelope. Duration of theenvelope is defined by the MIDIcommand CC 57.

Velocity 101 – 127 = NOTE ON + ACCENT.Triggers the envelope. Duration of the envelope is constant ~250mS. Value of the accent is added to the levelvalue of the note. Accent is definedby the MIDI command CC58.

FunctionAUTO-SLIDEis constantly turned on onlyin this mode and istriggered when notes overlap.

This mode is more suitable for playing over MIDI keyboard, as well as controlling the unit via MIDI file, while sequencer mode is more suitable for work with older sequencers that don't have note overlap function, but can also be used for work with MIDI files (easier input of sequences from other basslines).

MIDI CONTROL CHANGE MESSAGES

Midi CC 7 Volume.

idi CC 53 Filter Pre-Gain.

Midi CC 54 Cut-Off.

Midi CC 55 Resonance.

Midi CC 56 Envelope modulation.

Midi CC 57 Envelope Decay.

Midi CC 58 Accent.

Midi CC 59 Distort Gain.

Midi CC 60 Cut-Off step.

Midi CC 123 ALL NOTES OFF.

(default value =127).Astandarddefined CC message – output volume level.In 127 steps of 0.5dB, where value 0 is value for MUTE,and value 127 =0db (relative) maximum outputlevel. Steps are logarithmic,and transition between thesteps is linear for a smooth transition.

(default value = 0). Controls input signal level into the filter. Low value, hard resonance, but soft sound.

Higher value, lower resonance,but harder sound. Values from 0 to 127.

(default value = 0). Controls cuttingfrequency of thefilter. Works inconjunction with commandCC 56. Values from 0

to 127.

(default value = 0). Controlsthe signal level brought from output to input of the filter. Feedback. Values from 0 to

127. Value112 is optimal, while127 is near the selfoscillationof the filter.

(default value = 0). Controls the signal envelope level brought to the control level of the filter and

affects the cutting frequency ofthe filter.Envelope is logarithmic. Values from 0 to 127.

(default value = 0). Controls duration of the note without accent. Values from 0 to 127. Duration from

~250mS to ~2s.

(default value = 0). Controls intensity of the accent on notes with accent. Values from 0 to 127. When in CC 55 resonance is minimum value, envelope which comes to filter is logarithmic, but when CC 55 resonance is at maximumvalue, envelope is softened logarithmic and soundslike a little ducky effect.

(default value = 4, gain x2). Controls level of the sound coming out of the controlled amplifier. Values from 0 to

127. Where values from 0 – 3 mean direct throughput without amplification, and rest of the values are MIDI Value 4 – 127 / 2 = amplification 2x to 63x. It leads to hard cutting off of top of the signal, depending on the value (HARD CLIPPING DISTORTION) and makes distortion of thesound.

(default value = 30) Controls fluency of the change to the cut-off filter, that is speed of step change to the MIDI

command CC 54. Values0 to 127.

Used as PANIC command. In case the note didn't get turned off , sending this command

note is turned off instantly. Value doesn't affect execution ofthe command.

for some reason

Electrical data:

Power supply : +10V to +13V max,DC Current consumption: max. 100mA

MIDI input separated byopto-coupler.

Maximum output voltage: approx. 2.2VRMS = 6.2V peak-to-peak output impedance 1MOhm, approx. 1.95VRMS = 5.5V peak-to-peak output impedance 10kOhm (measured with generated SINE wave directly towards DAC, measured on the 6.35mm jack). Output impedance > 10KOhm.

Notes are in rangefrom 32.70Hz to 523.25Hz, thatis MIDI note 24 toMIDInote 72 (C1 – C5)(maximum deviation +/-1.5 cents).

BassBoy

MikroElektronika

technical support : andigo.office@gmail.com

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GND

10uF

tant 16V

GND

MIDI CHANNEL & MODE

100K

GND

10K

+3.3V

220

1 2

CN3

MIDI IN

OPTO1

CNY17-3

330u

C11

330u

C14

100nF

C12

100nF

C13

GND

ADC1/PA1

ADC0/PA0

ADC2/PA2

ADC3/PA3

ADC4/PA4

ADC5/PA5

ADC6/PA6

ADC7/PA7

(SPI)SCK/PC7

(SPI)MISO/PC6

(SPI)MOSI/PC5

(SPI)SS/PC4

TXD0/PC3

RXD0/PC2

(TWIC)SCL/XCK0/PC1

(TWIC)SDA/PC0

PB3/ADC11

PB2/ADC10

PB1/ADC9

PB0/ADC8

PD7/CLKOUT/SCK(SPID)

PD6/MISO(SPID)

PD5/MOSI(SPID)

PD4/SS(SPID)

PD3/TXD1

PD2/RXD1

PD1/XCK1

PD0

PE3

PE2

PE1/SCL(TWIE)

PE0/SDA(TWIE)

GND8GND18GND30GND

VCC9VCC19VCC

AVC C

RESET/PDI_CLK

PDI_DATA

PR1/XTAL1

PR0/XTAL2

U1 ATXMEGA32D4

Gnd

+3.3V

GND

100nF

GND

+3.3V

100nF

GND

+3.3V +3.3V

10K

MIDI RX

DAC CLK

DAC DATA

DAC WS

MIDI RX

CN2

GND

CLOCK

32.000MHz

SELECT

GND

IN3OUT

OUT

TLV1117-3.3

GNDGND GND GND

+3.3V

PDI_PGM

GND

DC POWER SUPPLY

1 2

CN4

OUT

6.35mm JACK

10K

3K3

1K5

+3.3V

GND

15pF C16

15pF C15

GND GND

CR1

8.000MHz

1 2 3

CN5

LEDS

MIDI DATA

OUT

GND

OSC1

8.000MHz

GND

OPTIONAL EXTERNALCLOCK

+3.3V

DAC DATA DIN

BCKIN

LRCIN

MCLK

VOUTR

VDD

GND

VOUTL

WM8762

DAC CLK

DAC WS

GND

100nF

+3.3V

10uF

tant 16V

GND

CLOCK

CLK

VDD

GND

CLR

U2A

MC74HC74AD

VDD

GND

CLK

CLR

U2B

GND

16.000MHz

32.000MHz

+3.3V

GND

+3.3V

Q1 BC550C

Q2 BC560C

3K3

R10

100

R11

10uF

tant 16V

+3.3V

+VCC

10K

R12

GND

100K

R13

R14

10uF C9

tant 16V

GND

+VCC

100nF

GND

1N4148

D4 D5 D6 D7

D2 ... D7 = 1N4007

100K

R15

GND

1 2

3 4

5 6

7 8

9 10

CN1

100nF

C10

GND

+3.3V

GND

100nF

C17

2SC2240

2SA970

AUDIO OUTPUT

BassBoy

MikroElektronika

technical support : andigo.office@gmail.com

Figure 1-4: BassBoy MIDI device schematic

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BassBoy

MikroElektronika

technical support : andigo.office@gmail.com