Difference between revisions of "F21: Treasure Dive"

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(I2S Peripheral and Stereo Audio Decoder)
(Hardware Interface)
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[[File:CMPE146_F16_MW_XbeeModule.jpg|200px|thumb|center|XBee Device]]
[[File:CMPE146_F16_MW_XbeeModule.jpg|200px|thumb|center|XBee Device]]
[[File:sj2Board.png|200px|thumb|center|SJ2 Board]]
Two LED buttons were used to interface with the controller as inputs. They were both set up using GPIO.
Two LED buttons were used to interface with the controller as inputs. They were both set up using GPIO.

Revision as of 11:00, 18 December 2021

Game Screen Capture
Game Controller

Grading Criteria

  • How well is Software & Hardware Design described?
  • How well can this report be used to reproduce this project?
  • Code Quality
  • Overall Report Quality:
    • Software Block Diagrams
    • Hardware Block Diagrams
      Schematic Quality
    • Quality of technical challenges and solutions adopted.

Treasure Dive


Treasure Dive is a modern one player game inspired by the popular arcade game Breakout, which was released by Atari in 1976. The ancients rambled about an unconfirmed tale of a shipwreck that saw no survivors. As an adventurous and skilled free diver, you are seeking treasure buried deep in an ocean abyss. You dove down all the way to the seafloor and found the buried treasure but need to make it back to the surface to see another day! The player uses a wireless controller to control an on-screen paddle to break bricks on the top of the screen. When enough bricks are broken, a passage is revealed, allowing you to get closer to the surface.

Objectives & Introduction

The objective of this project is to interface an LPC4088 to a VGA monitor by leveraging the LCD controller and use an accelerometer as the sensor for the player to control the paddle. Two Zigbees RF modules will be integrated for wireless communication between the controller and LPC4088 board via UART protocol. Digital audio output will be enabled by developing an I2S driver and porting an audio tracker library. The General Purpose Direct Memory Access (GPDMA) controller memory-to-memory function will be utilized to decrease memory write times when updating the video buffer. The DMA controller's memory-to-peripheral function will help reduce the frequent I2S interrupts when loading digital audio contents. An SD card peripheral driver to facilitate memory exchange between an SD card will also be implemented.

Team Members & Responsibilities

  • Brian Ho
    • Wiki project schedule planning
    • Interfacing the accelerometer
    • Digital to Analog Conversion resistor ladder design used to interface digital LCD controller signal with analog VGA port signal
    • PCB planning and acquisition
    • Procurement of controller hardware
    • Wireless communication via Zigbees RF modules and UART protocol
    • Wireless controller logic and integration
    • Ball movement and wall/brick collision logic
    • Hardware/software development and integration
    • Final testing and integration
  • Billy Lai
    • Wiki project schedule planning
    • Increased CPU clock rate from 96 MHz to 120 MHz
    • Initial memory write timing and measurements to estimate memory write capacity
    • DMA driver memory-to-memory implementation for transferring graphics data to video buffer
    • I2S with DMA memory-to-peripheral implementation to reduce memory-write interrupts when I2S Tx FIFO level is low
    • Paddle movement and paddle collision logic, testing and integration
    • Software development and integration
    • Final testing and integration
  • Jasdip Sekhon
    • Wiki project schedule planning
    • PCB design and planning
    • File loading method algorithm for storing loaded files in memory
    • Audio track and audio effects selection for gameplay audio
    • Palette manipulation for gameplay
    • Software development and integration
    • Final testing and integration
  • Isaac Wahhab
    • Wiki project schedule planning
    • DAC resistor ladder design and integration
    • Hardware procurement (LPC4088 board, Zigbees, VGA monitor, etc)
    • VGA driving through LCD controller
    • Audio tracker library port
    • Digital audio output using I2S
    • Palette scrolling feature implementation
    • Graphics rendering
    • Vertical scrolling implementation for the video buffer
    • Sprite testing and implementation for the ball
    • SD card peripheral driver for reading assets from SD card
    • Art assets acquisition
    • Hardware/software development and integration
    • Gameplay logic design
    • Gameplay audio and level design
    • Final testing and integration


Week# Start Date End Date Task Status
  • 09/21/2021
  • 09/27/2021
  • Read previous projects, gather information and discuss among the group members.
  • Initial ordering of parts (LPC 4088 board, 64x64 LED screen)
  • Completed
  • Completed
  • 09/28/2021
  • 10/04/2021
  • Submit project proposals
  • Completed
  • 10/05/2021
  • 10/11/2021
  • Test if board can drive VGA
  • Test varying clock rates
  • Hardware cursor on VGA
  • Rough display driver
  • Completed
  • Completed
  • Completed
  • Completed
  • 10/12/2021
  • 10/18/2021
  • DAC resistor ladder
  • RGB channels
  • Palette shifting
  • Measure memory buffer writing timing
  • Wiki schedule planning
  • Completed
  • Completed
  • Completed
  • Completed
  • Completed
  • 10/19/2021
  • 10/25/2021
  • Calculate upper-bound for VGA refresh timings
  • Create GitLab repository for project
  • Joystick functionality
  • SD card driver
  • Completed
  • Completed
  • Completed
  • Completed
  • 10/26/2021
  • 11/01/2021
  • Audio peripheral
  • Wireless communication using Zigbee module
  • PCB planning
  • Accelerometer driver
  • Continue SD card driver
  • Completed
  • Completed
  • Completed
  • Completed
  • Completed
  • 11/02/2021
  • 11/08/2021
  • Continue audio peripheral
  • Continue wireless communication using Zigbee module
  • Continue accelerometer driver
  • PCB finalizing and ordering
  • Completed
  • Completed
  • Completed
  • Completed
  • 11/09/2021
  • 11/15/2021
  • Convert PNG data to graphics format
  • Game background functionality
  • Sprite functionality
  • User interface
  • Integrate components
  • Initial testing
  • Completed
  • Completed
  • Completed
  • Completed
  • Completed
  • Completed
  • 11/16/2021
  • 11/22/2021
  • Continue everything from last week
  • Game physics (wall collision and AI movement)
  • Measurements for wooden case
  • Art assets (audio and visual)
  • Completed
  • Completed
  • Completed
  • Completed
  • 11/23/2021
  • 11/29/2021
  • Fine-tune user experience
  • Make case
  • Completed
  • Completed
  • 11/30/2021
  • 12/06/2021
  • Continue fine-tune user experience
  • Integrate hardware
  • Completed
  • Completed
  • 12/07/2021
  • 12/16/2021
  • Final testing
  • Final demo
  • Completed
  • Completed

Bill Of Materials

Item# Part Description Part Model & Vendor Quantity Cost
1 Microcontroller Board LPC4088-32 Developer's Kit 1 $300.00
2 Microcontroller Board SJ2 Board 1 $50.00
3 Bluetooth Module Digi XBee-S1 2 N/A
4 DAC PCB JLCPCB (Set of 5) 1 $15.00
4 Monitor Asus TFT Monitor 1 N/A
5 Mini Breadboard ELEGOO Mini Breadboard 1 $13.99
6 Arcade buttons EG STARTS LED Arcade Buttons 2 $11.99
7 VGA cable N/A 1 N/A
7 SD card N/A 1 N/A

Design & Implementation

Hardware Design

We designed our PCB using Autodesk EAGLE based on the tutorial on PCB design during the class lecture. We ordered our PCB to be manufactured from JLCPCB. The PCB consists of an R-2R resistor ladder DAC for the purpose of converting the digital signal from the microcontroller to analog to display graphics on the VGA monitor. Since the VGA input for each color channel is 0-0.7V, the resistor ladder scaled the LPC4088 outputs into proper DAC values for the VGA to take in. Five bits are passed to each of the red, green, and blue channels of the VGA in addition to other signals, such as Horizontal sync (HSYNC) and Vertical sync (VSYNC).

PCB Schematic
PCB Layout
Manufactured PCB
Soldered PCB

Hardware Interface

Two Digi XBee devices were used to communicate between the SJ2-Board controller and the LPC4088 board to control the paddle on the game. The XBee devices were programmed using the XTCU programming application provided by Digi International. The SJ2-Board used one XBee as a transmitted and the LPC4088 used another as a receiver. The two modules communicated using UART frames and a single byte represented any change of movement or button presses sent by the controller.

XCTU Transmitter Receiver
ID 6969 6969
CE Coordinator Endpoint
Baud Rate 9600 9600
XBee Device
SJ2 Board

Two LED buttons were used to interface with the controller as inputs. They were both set up using GPIO.

LED Button

Controller Block Diagram

I2S Peripheral and Stereo Audio Decoder

The LPC4088 is equipped with an I2S stereo encoder. This module provides a hardware-enabled solution for sending I2S-encoded audio data packets to stereo decoders, which produce the corresponding audio waveform. For this project, since 16-bit stereo audio playback was chosen, data packets transmitted on this interface were sent in the following format:

I2S audio data word.png

Here, each word of data encodes a single packet of audio in two 16-bit sections: one signal level for the left channel, and another for the right. These 4 bytes are sent at a rate of 44100 Hz, resulting in a total data transmission of 176400 bytes a second. Rather than needing to be software-defined, this transmission is automatically handled by hardware using a 8-word deep FIFO queue that manages streaming out the audio data at a fixed rate, saving a significant amount of CPU cycles.

This encoded audio signal was sent to a dedicated external stereo decoder, which output to a 3.5 mm audio jack connected to speakers in the VGA monitor.

LCD Peripheral

External Memory

Software Design

Show your software design. For example, if you are designing an MP3 Player, show the tasks that you are using, and what they are doing at a high level. Do not show the details of the code. For example, do not show exact code, but you may show pseudocode and fragments of code. Keep in mind that you are showing DESIGN of your software, not the inner workings of it.


There is an internal accelerometer on the SJ2 board that is utilized as the movement controls for the paddle movement. The y-axis value of the magnitude is polled 17 times in 17 milliseconds and is divided by 17 to get an average reading per that time frame. The maximum tilt value that can be read by the controller is set to 700 out of the total 1000 (highest possible value). The current tilt value is divided by 31 to get a total of 32 possible readings to represent 5 bits of magnitude.

The controller sends one byte of data to the console whenever there is any change in magnitude on the accelerometer or button changes. The byte contains all the information needed to control the paddle on the screen. The first two bits on the byte represent 0 if there is no button input and 1 if there is a button input. The third bit represents whether the controller is tilted left or right with 0 being left and 1 being right. The last five bits represent the controller accelerometer's magnitude.



Sound design was provided to the project (in the form of music and sound effects) through the use of a tracker audio library. Source code was adopted from the Schism Tracker library and altered with the following modifications:

- All UI logic was stripped from the source code

- All file handling logic was reworked to use the SD card reading functions, as the project does not support POSIX file calls

- The Simple DirectMedia Layer hooks were replaced with a FreeRTOS task that periodically called the waveform generation callback function, which was passed to the I2S peripheral hooked up to a stereo decoder.


This section includes implementation, but again, not the details, just the high level. For example, you can list the steps it takes to communicate over a sensor, or the steps needed to write a page of memory onto SPI Flash. You can include sub-sections for each of your component implementation.

Ball Logic

The ball is controlled by the buttons and the controller accelerometer values. When the button is pressed, the ball is initially sent with a random velocity. The velocity is determined by a substate timer and is initially set as one of 6 possible values.

Substate Count X-Velocity Y-Velocity
0 4 -2
1 -4 -2
2 2 -4
3 -2 -4
4 1 -5
5 -1 -5

The ball's velocity changes whenever it detects a collision with either the side of the screen, the bricks on the top of the level, or the paddle at the bottom. If colliding with the paddle, the ball's velocity will take into account the paddle's velocity and add it to its current velocity. This is done by adding the paddle's x-velocity and adjusting the y-velocity by normalizing the velocity vectors to have a magnitude of 5. This means the ball will always be moving with a magnitude of 5 in any direction after it hits the paddle. If the ball collides with anything other than the paddle, then the velocity of the ball is changed with no increase or decrease of magnitude. If the ball collides on the side of a wall or block, the x-velocity will reflect (go from negative to positive or vice-versa) and the y-velocity will remain constant. If the ball collides on the top or bottom of a block, the y-velocity will reflect and the x-velocity will remain constant. If it appears that the ball collides with the side and top or bottom of something, then the ball will check whichever face it will collide with first and then calculate the other face. Lastly, when the ball collides with the bottom of the screen, then the player experiences a "death" and the ball will reset on the paddle. If the ball collides with the top of the screen, the screen will scroll up for the user to play on the next level.

Whenever the ball collides with a brick, the brick will disappear. To accomplish this, there is a 2-D array of unsigned integers that contains the values of the bricks. If the integer is 0, then there is no block. If the integer is any value other than 0, then the block is filled and has collision logic. If the ball approaches a region that might have a block, then there will be a check within that 2-D to see if the block is filled or empty. If the block is filled, there will be the collision logic that changes the vector of the ball and sets the integer value in the 2-D array to 0 to represent that the block has been broken.

Paddle Movement

The paddle movement is controlled by the accelerometer data being wirelessly transmitted from the SJ-Two board to the LPC4088 board. The accelerometer data will map to 63 possible indexes for the paddle location. Originally, the paddle would jump directly into the corresponding index location depending on the accelerometer input. We later iterated on this process by implementing an algorithm to smoothly transition into these indexes. This was done by calculating a paddle velocity using the "current desired paddle position" and the previous paddle position. We adjusted the parameters of the algorithm iteratively to produce the smooth paddle movement.

Testing & Technical Challenges

Describe the challenges of your project. What advise would you give yourself or someone else if your project can be started from scratch again? Make a smooth transition to testing section and described what it took to test your project.

Include sub-sections that list out a problem and solution, such as:

VGA Interfacing

A DAC resistor ladder was designed and a corresponding custom PCB was acquired to interface the 3.3V digital LCD controller signal with the analog VGA input signal. The VGA cable takes between 0V (completely dark) and 0.7V (maximum brightness) for color pin inputs. The DAC resistor ladder was designed and implemented on a breadboard to verify the design. Validating the design on a breadboard gave us a clear vision during PCB design and planning.

VGA Write Timings

There were initial tests that were required to be done to see if using a VGA monitor as an output was a viable option for this project. We had to test memory write timings to see if they were fast enough to match the refresh rate of the monitor. Those tests would decide how much of the screen buffer we could write to during the blanking periods during the VGA refresh. This was a good learning experience for testing hardware capabilities and should be done whenever introducing any new aspects to a project.

Ball Collision Logic

The initial version of the ball collision used pixel values to see if the ball was entering the brick. The problem was that this logic did not account for the case where the ball enters the brick diagonally and the logic for that version of the collision had to be scrapped. The later iteration of the logic was changed to checking whether the ball was potentially crossing into an area that had a brick. This was done by separating the checks into a grid that represented the locations of the blocks. In this case, there was an initial check to see if the ball was crossing a boundary where there might be a new brick. If the ball is crossing the x-boundary and not the y-boundary, then there would be a collision check to see if it collided with a block. If it is crossing the y-boundary and not the x-boundary, once again then there would be a collision check to see if it collided with a block. If it is crossing both the x-boundary and y-boundary, then there would be a check to see which boundary the ball would cross first. This new logic allowed for us to account for the case where the block enters the block diagonally. This taught us that sometimes it is beneficial to scrap a previous iteration and use a new approach to solving a problem because it may lead to better results.

Paddle Movement and Paddle Collision Logic

The paddle movement is controlled by the accelerometer data being wirelessly transmitted from the SJ-Two board to the LPC4088 board.


Conclude your project here. You can recap your testing and problems. You should address the "so what" part here to indicate what you ultimately learnt from this project. How has this project increased your knowledge?

Project Video

SJSU CMPE 244 FALL 2021: Embedded Software Project Gameplay

Project Source Code



Any acknowledgment that you may wish to provide can be included here.

References Used


You can list the references you used.