Linker 3000
BBC micro:bit SN76489N VGM chiptunes player
Diff: main.cpp
- Revision:
- 1:09a3520030b4
- Parent:
- 0:e4dc860c8472
- Child:
- 2:74ecf50e4424
--- a/main.cpp Sun Feb 04 21:13:17 2018 +0000
+++ b/main.cpp Sun Feb 11 11:10:58 2018 +0000
@@ -1,57 +1,222 @@
/*
-The MIT License (MIT)
+BBC micro:bit VGM player
-Copyright (c) 2018 Linker3000 (N. Kendrick - linker3000-at-gmail-dot-com).
+Version: 0.1 NK 10-Feb-2018
+
+Copyright 2018 N Kendrick (nigel-dot-kendrick-at-gmail-dotcom)
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
-and/or sell copies of the Software, and to permit persons to whom the
-Software is furnished to do so, subject to the following conditions:
+and/or sell copies of the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-DEALINGS IN THE SOFTWARE.
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+Inspired by Arduino code produced by Artkasser (https://github.com/artkasser)
+
+This code plays BBC micro (SN76489) VGM sound files on a BBC micro:bit.
+
+Note that in this code version, the VGM data is stored as a byte array file
+(minus the header info), and not read-in from anywhere. Maybe later!?
+
+External circuitry is needed to make this work:
-Proof of concept - BBC micro:bit SPI functionality to send serial data to
-a 74HC595 shift register.
-
-Version: 0.1 NK 04-Feb-2018
+1 x BBC micro:bit breakout board (eg: Kitronik) to get to the required pins
+1 x SN74HC595 shift register IC - easy to obtain
+1 x SN76489 programmable sound generator (PSG) IC (From a reputable[!]
+ supplier. You can get them on Ebay and elsewhere but beware of fakes.
+2 x 0.1uF ceramic capacitors
+1 x 4MHz oscillator module - the connections list below assumes a '14-pin'
+ unit - such as something similar to QX14T50B4.000000B50TT.
+ Note, you want a 4MHz crystal MODULE, not a 4MHz crystal.
+1 x Breadboard to build the circuit, unless there is room on the breakout board
+ or you use perfboard/stripboard or make your own PCB etc.
+2 x 16-pin IC sockets (optional, and not needed for a breadboard)
+1 x audio amplifier or lead to connect PSG audio out to a set of active
+ speakers, you could instead connect a pieze element (not a buzzer) to the
+ audio out pin of the PSG. If connecting to a piezo sounder, you'll need a
+ 1K resistor.
+1 x Assorted wiring
Connections:
-Microbit Function 74HC595
- P0 MOSI Pin 14 (SER)
- P1 CE Pin 12 (RCLK)
- P2 SER Pin 11 (SRCLK)
- GND ~CE Pin 8, Pin 13 (~CE)
- VCC (3.3v) VCC Pin 16
-
-
-Connect LEDs to 74HC595 outputs (via 470Ohm-1K resistors) to see output.
-For stability, connect a 0.1uF capacitor between VCC and GND on the 74HC595
-chip, as close to its body as possible.
+ The micro:bit takes power as usual from the connected micro USB cable.
+
+ Everything else i powered from a separate 5V supply, such as a USB phone
+ charger. You *could* try powering these parts from the 3V connection on
+ the micro:bit - it might work, but the PSG and the oscillator module are
+ officially 5V parts so YMMV.
+
+ Remember to ensure that the micro:bit's 0V/GND line is connected to the
+ GND line of all the other parts to ensure proper circuit operation. DO NOT
+ connect the 5V power line to the micro:bit's 3V line as you'll break
+ something!
+
+ Hookup overview:
+
+ From Function Connect to
+ micro:bit P15 MOSI 74HC595 pin 14 (SER)
+ micro:bit P13 CE 74HC595 pin 12 (RCLK)
+ micro:bit P2 SER 74HC595 pin 11 (SRCLK)
+ micro:bit P8 PSG ~WE SN76489 pin 5 (~WE)
+ 74HC595 Data out Data bus PSG Data lines - Note that the PSG data
+ lines are labelled in REVERSE, so the
+ wiring between the 595 and the 76489 should
+ be 74HC595 D0 --- D7 SN76489
+ 74HC595 D1 --- D6 SN76489 etc
+ Oscillator P7 GND To common ground with all other GND pins
+ Oscillator P8 CLK SN76489 pin 16
+ Audio out AUDIO SN76489 pin 7 to an external amplifier,
+ or a piezo sounder through a 1K resistor
+ +5V VCC Both ICs, pin 16, Oscillator pin 14; all
+ active components EXCEPT the micro:bit
+ micro:bit GND GND connect to the common GND on the external
+ parts
+
+For stability, connect 0.1uF capacitors between VCC and GND near the both the
+74HC595 and SN76489 chips.
+
+Double-check all wiring before powering up anything!
*/
#include "MicroBit.h"
#include "nkpins.h"
+//VGM file as a byte array with header info removed...
+#include "sonic.h"
+
MicroBit uBit;
+MicroBitDisplay display;
+
+const uint16_t SampleTime = 23; //VGM format = 44,100Hz sampling = 23uS/sample
+
+// General program variables
+
+uint16_t Samples = 0;
+uint16_t vgmpos = 0;
+
+// Microbit SPI port setup
+// Using the default SPI pins defined in the micro:bit docs...
+SPI spi(mbit_p15, mbit_p14, mbit_p13); // mosi, miso (not used), sclk
+DigitalOut cs(mbit_p1); //Chip select pin for the shift register
+DigitalOut PSG_WE(mbit_p8); //~WE pin for PSG
+
+void PutByte (uint8_t b)
+// Write data to the shift register via SPI interface
+{
+ cs = 1;
+ spi.write(b);
+ cs = 0;
+}
+
+void SendByte(uint8_t b)
+{
+ PSG_WE = 1;
+ PutByte(b);
+ PSG_WE = 0;
+ wait_us(SampleTime);
+ PSG_WE = 1;
+}
+
+void SilenceAllChannels()
+{
+ SendByte(0x9f);
+ SendByte(0xbf);
+ SendByte(0xdf);
+ SendByte(0xff);
+}
+
+void Playloop()
+//Process the VGM data
+{
+
+ bool runstop = false;
+ // True when we get to the 'end of data' value in the array.
+ // There's no current trap for if the last byte in the array isn't 0x66
+
+ do {
+ uint8_t vgmdata = (*(VGMDataArray + vgmpos));
+
+ // Process VGM codes.
+
+ /* Some ranges are reserved for future use, with different numbers of
+ operands:
-// Moving SPI pins we want to use to the large P0 etc connections.
-// miso remains on the default pin definition as we're not using it here
-SPI spi(mbit_p0, mbit_p15, mbit_p2); // mosi, miso, sclk
-DigitalOut cs(mbit_p1); //Chip select pin for the shift register
+ 0x30..0x3F dd : one operand, reserved for future use
+ Note: used for dual-chip support
+ 0x40..0x4E dd dd : two operands, reserved for future use
+ Note: was one operand only til v1.60
+ 0xA1..0xAF dd dd : two operands, reserved for future use
+ Note: used for dual-chip support
+ 0xBC..0xBF dd dd : two operands, reserved for future use
+ 0xC5..0xCF dd dd dd : three operands, reserved for future use
+ 0xD5..0xDF dd dd dd : three operands, reserved for future use
+ 0xE1..0xFF dd dd dd dd : four operands, reserved for future use
+
+ This programming does NOT currently cater for those codes
+ */
+
+ if ((vgmdata & 0xF0) == 0x70) {
+ // 0x7n : wait n+1 samples, n can range from 0 to 15
+ //Samples = 1;
+ vgmpos++;
+ wait_us(((vgmdata & 0x0F)+1) * SampleTime);
+ } else {
+ switch (vgmdata) {
+ case 0x50: // 0x50 dd : PSG (SN76489/SN76496) write value dd
+ vgmpos++;
+ vgmdata = (*(VGMDataArray + vgmpos));
+ SendByte(vgmdata);
+ vgmpos++;
+ break;
+ case 0x61: // 0x61 nn nn : Wait n samples, n can range from 0 to 65535
+ vgmpos++;
+ Samples = (uint16_t)( (*(VGMDataArray + vgmpos)) & 0x00FF );
+ vgmpos++;
+ Samples |= (uint16_t)(( (*(VGMDataArray + vgmpos)) << 8) & 0xFF00 );
+ vgmpos++;
+ wait_us(Samples * SampleTime);
+ break;
+
+ case 0x62: // wait 735 samples (60th of a second)
+ vgmpos++;
+ wait_ms(17);
+ break;
+
+ case 0x63: // wait 882 samples (50th of a second)
+ vgmpos++;
+ wait_ms(20);
+ break;
+
+ case 0x66: // 0x66 : end of sound data
+ vgmpos = 0;
+ SilenceAllChannels();
+ wait_ms(2000);
+ runstop = true;
+ break;
+
+ default:
+ break;
+ } //end switch
+
+ } // end else
+
+
+ } while (!runstop);
+}
int main()
{
// Initialise the micro:bit runtime.
@@ -62,33 +227,26 @@
cs = 1;
// Setup the spi for 8 bit data, high steady state clock,
- // second edge capture, with a 1MHz clock rate
+ // second edge capture, with a 1MHz clock rate (microbit and shift
+ // register can handle it - tested).
spi.format(8,3);
spi.frequency(1000000);
-
- // Select the device by setting chip select low
- cs = 0;
+
+ // Silence the PSG
- // Load up the shift register
- while(1){
- cs = 1;
- spi.write(0x55);
- cs = 0;
- wait(0.5);
+ PSG_WE = 1;
+ SilenceAllChannels();
+ wait_ms(500);
- // Load up alternate bits
- cs = 1;
- spi.write(0xAA);
- cs = 0;
- wait(0.5);
- }
-
- // If main exits, there may still be other fibers running or registered event handlers etc.
- // Simply release this fiber, which will mean we enter the scheduler. Worse case, we then
- // sit in the idle task forever, in a power efficient sleep.
-
- // We'll never get here unless something goes very wrong.
- release_fiber();
+ //Play music
+ Playloop();
+ //Mute the last tone
+ SilenceAllChannels();
+
+ display.scroll("** DONE ** :)");
+
+ //Tidy up and we're done
+ release_fiber();
}