Part 1. MAX BIT DAC with an Arduino Board. MIDI to Voltage Converter Part1

Transcription

1 MIDI to Voltage Converter Part 1 MAX BIT DAC with an Arduino Board 1

2 What you need: 2

3 What you need : Arduino Board (Arduino Mega 2560) 3

4 What you need : Arduino Board (Arduino Mega 2560) Digital Analog Converter with SPI (MAX525) 4

5 What you need : Arduino Board (Arduino Mega 2560) Digital Analog Converter with SPI (MAX525) MIDI Plug + Opto coupler 5

6 Arduino Board Arduino Mega RX 13 Gate 51 SDI 52 CLK 53 CS 6

7 Arduino Board + SPI Converter Arduino Mega RX 13 Gate SPI Converter Gate 51 SDI 52 CLK 53 CS SDI CLK CS Out CV 7

8 Arduino Board + SPI Converter + Midi Board Midi Board Arduino Mega 2560 SPI Converter RX 1 RX 13 Gate Gate 51 SDI 52 CLK 53 CS SDI CLK CS Out CV 8

9 DAC Converter Board On the board there is MAX525 with 4 12bit DACs inside. Beside the converter and the buffer OpAmps there is a LT1236 5V voltage reference and a 74HC14. I use LF356 as Buffer OpAmps. The output voltage range is 0 to 2V 9

10 DAC Converter Board LT1236 LF356 Reference voltage is trimmed to 2V +-15V +5V Output Vref = Vdd -1,4V!! See Datasheet page 8. Ouput Port B SPI 74HC14 MAX525 10

11 SPI Connector SDO (Serial Data Out) / MISO (Master in, Slave out) SDI (Serial Data In) / MOSI (Master out, Slave in) SCK (Serial Clock) / SCLK CS (Chip Select) 11

12 SPI Communication Timing CS SCK SDI 12

13 SPI Communication Timing CS SCK SDI If the chip select pin gets low the data on the SDI pin is transfered to the internal register on every falling edge of the clock signal. 13

14 SPI Communication Timing CS SCK SDI If the chip select pin gets low the data on the SDI pin is transfered to the internal register on every falling edge of the clock signal. With the rising edge of the chip select the data is transfered to the DAC output. 14

15 The serial Datastructure 15

16 The serial Datastructure MSB 16 Bit seriel data LSB 16

17 The serial Datastructure MSB 16 Bit seriel data LSB Address Bits Control Bits Data MSB LSB A1 A0 C1 C0 D11..D0 17

18 The serial Datastructure MSB 16 Bit seriel data LSB Address Bits Control Bits Data MSB LSB A1 A0 C1 C0 D11..D0 4Address/ Control Bits 12 databits 18

19 MSB and LSB 4Address/ Control Bits 12 databits MSB LSB 19

20 MSB and LSB MSB LSB

21 MSB and LSB MSB LSB This command is loading all DAC registers with the value of the input register. All outputs have the same value. See datasheet page 10 table 1. 21

22 MSB and LSB MSB LSB

23 MSB and LSB MSB LSB Volt output voltage 23

24 Timing chart Output value 0 CS SCK SDI 24

25 Timing chart Output value 0 CS MSB SCK SDI 25

26 Timing chart Output value 0 CS SCK SDI MSB LSB 26

27 MSB and LSB MSB LSB

28 MSB and LSB MSB LSB Output voltage = VRef * (Value/4096) 28

29 MSB and LSB MSB LSB Output voltage = 2V * (4095/4096) = 1,99V 29

30 Timing chart Output value 4095 CS SCK SDI 30

31 Timing chart Output value 4095 CS MSB SCK SDI 31

32 Timing chart Output value 4095 CS SCK SDI MSB LSB 32

33 Program sequence 33

34 Program sequence Define the CS pin, settting to output, set value = high 34

35 Program sequence Define the CS pin, settting to output, set value = high Activate SPI interface 35

36 Program sequence Define the CS pin, settting to output, set value = high Activate SPI interface Setting the SPI parameter 36

37 Program sequence Define the CS pin, settting to output, set value = high Activate SPI interface Setting the SPI parameter Set CS = low -> shifts the following data to the input register 37

38 Program sequence Define the CS pin, settting to output, set value = high Activate SPI interface Setting the SPI parameter Set CS = low -> shifts the following data to the input register Transmit MSB thru SPI 38

39 Program sequence Define the CS pin, settting to output, set value = high Activate SPI interface Setting the SPI parameter Set CS = low -> shifts the following data to the input register Transmit MSB thru SPI Transmit LSB thru SPI 39

40 Program sequence Define the CS pin, settting to output, set value = high Activate SPI interface Setting the SPI parameter Set CS = low -> shifts the following data to the input register Transmit MSB thru SPI Transmit LSB thru SPI Set CS = high -> shifts the value to the output register of the DAC 40

41 End Part 1 MAX 525: LT1236: LF356: 6N139: 74HC14: Arduino: 41