From 85257fafc0e5409c1d8024094cbaf81d916a58f0 Mon Sep 17 00:00:00 2001 From: rej Date: Thu, 9 Nov 2023 09:39:47 +0100 Subject: [PATCH] Fixing headers --- info.yaml | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/info.yaml b/info.yaml index 8b778ec..f639dff 100644 --- a/info.yaml +++ b/info.yaml @@ -62,7 +62,6 @@ documentation: | 2 | Channel #2 attenuation | Tone #2 frequency | | 3 | Channel #3 attenuation | Noise type and frequency | - ___Square wave tone generators___ Square waves are produced by counting down the 10-bit counters. Each time the counter reaches the 0 it is reloaded with the corresponding value from the configuration register and the output bit of the channel is flipped producing square waves. @@ -103,7 +102,7 @@ documentation: ``` - ** Difference from the original hardware ** + **Difference from the original hardware** This Verilog implementation is a completely digital and synchronous design that differs from the original SN76489 design which incorporated analog parts. @@ -133,7 +132,7 @@ documentation: 3. high frequency clock configuration for TinyTapeout, suitable for a range between 25 MHz and 50 Mhz. In this configuration the master clock is internally divided by 128. - ** The reverse engineered SN76489 ** + **The reverse engineered SN76489** This implementation is based on the results from these reverse engineering efforts: @@ -143,7 +142,7 @@ documentation: # Instructions on how someone could test your project, include things like what buttons do what and how to set the clock if needed how_to_test: | - ** Connect chip to the speaker ** + **Connect chip to the speaker** There are several ways to connect this chip to a microcontroller and speaker. @@ -151,6 +150,7 @@ documentation: for example [Digilent R2R Pmod](https://digilent.com/reference/pmod/pmodr2r/start) to the output pins and route the resulting analog audio to piezo speaker or amplifier. + ``` uController SN76489 ,---------. ,---._.---. | | 4 Mhz ->|CLK SEL0|<-- 0 @@ -168,7 +168,7 @@ documentation: | `| | GND --- - + ``` ___AUDIO OUT through RC filter___ Another option is to use the Pulse Width Modulated (PWM) AUDIO OUT pin that combines 4 channels with the Resistor-Capacitor based low-pass filter or better the Operation Amplifier (Op-amp) & Capacitor based integrator: @@ -214,7 +214,7 @@ documentation: GND --- GND --- ``` - ** Summary of commands to communicate with the chip ** + **Summary of commands to communicate with the chip** Once playback schematics of the SN76489 are established, the controller program has to send data to the chip. SN76489 is programmed by updating its internal registers via data bus. @@ -235,7 +235,7 @@ documentation: | 1 | 0 | Clock divided by 2048 | | 1 | 1 | Use channel #2 tone frequency | - ** Note frequency ** + **Note frequency** Use the following formula to calculate the 10-bit value for a particular frequency: @@ -245,7 +245,7 @@ documentation: $$ n = 4000000 / (32 * 400) = 284 $$ - ** An example sequence of data commands to produce sound ** + **An example sequence of data commands to produce sound** Hold **/WE** low once data bus pins are set to the desired values. Pull **/WE** high again before setting different value to data bus. @@ -259,7 +259,7 @@ documentation: 11111000 - ---//--- volume to 50% (attenuation = 8) ``` - ** Timing diagram ** + **Timing diagram** ``` CLK ____ ____ ____ ____ ____ ____ __/ `____/ `____/ `____/ `____/ `____/ `___ ... @@ -282,7 +282,7 @@ documentation: ``` - ** Configurable clock divider ** + **Configurable clock divider** Clock divider can be controlled through **SEL0** and **SEL1** control pins and allows to select between 3 chip variants. @@ -293,7 +293,7 @@ documentation: | 0 | 1 | SN76494 mode, no clock divider | 250 .. 500 kHZ | | 1 | 0 | New mode for TT05, clock div. 128 | 25 .. 50 MHz | - ** Example music recorded from the chip simulation ** + **Example music recorded from the chip simulation** - [https://www.youtube.com/watch?v=ghBGasckpSY](Crazee Rider BBC Micro game) - [https://www.youtube.com/watch?v=HXLAdA02I-w](MISSION76496 tune for Sega Master System)