Application Note
AN_349
FT51A FT800 Spaced Invaders
Sample
Version 1.1
Issue Date: 2015-11-26
This document provides a guide for using the FT51A development
environment with an attached FT800 to play the Spaced Invaders game.
Use of FTDI devices in life support and/or safety applications is entirely at the user’s risk, and the
user agrees to defend, indemnify and hold FTDI harmless from any and all damages, claims, suits
or expense resulting from such use.
Future Technology Devices International Limited (FTDI)
Unit 1, 2 Seaward Place, Glasgow G41 1HH, United Kingdom
Tel.: +44 (0) 141 429 2777 Fax: + 44 (0) 141 429 2758
Web Site: http://ftdichip.com
Copyright © 2015 Future Technology Devices International Limited
Application Note
AN_349 FT51A FT800 Spaced Invaders Sample
V ers ion 1 .1
D oc ument Reference N o.: FT _001128
C learance N o.: FT DI# 4 3 0
Table of Contents
1 Introduction ............................................................ 3
1.1 Overview.......................................................................... 3
1.2 Features........................................................................... 3
1.3 Limitations ....................................................................... 3
1.4 Scope ............................................................................... 3
2 Firmware Overview ................................................. 4
2.1 FT800 Display................................................................... 4
2.2 FT51A Libraries ................................................................ 4
3 FT800 Spaced Invaders Firmware ............................ 5
3.1 Timer ............................................................................... 5
3.2 Writing to FT800 .............................................................. 6
3.3 How the Game Works ....................................................... 6
4 Possible Improvements ........................................... 7
5 Contact Information ................................................ 8
Appendix A – References ............................................. 9
Document References .............................................................. 9
Acronyms and Abbreviations .................................................... 9
Appendix B – FT800 and Joystick Schematic ............... 10
Appendix C – Revision History .................................... 11
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AN_349 FT51A FT800 Spaced Invaders Sample
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1 Introduction
This application note documents an example firmware project for the FT51A. The source code is
available in the “examples\ AN_349_FT51A_FT800_Spaced_Invaders_Sample” folder of the FT51A
Software Development Kit.
1.1 Overview
The application implements a version of the popular computer game ‘Space Invaders’. It will
render the game graphics on an FT800 display module. Input to control the game is via GPIO
signals.
The hardware modules required to use the application note are a VM800B module (FT800 and
display); either a UMFT51-AA or FT51A EVM (FT51A module); A joystick (or simply a left and right
button) and a fire button.
The FT800 on the VM800B module is connected to the SPI Master interface of the FT51A on pins
DIO_2 (Slave Select 1), DIO_3 (SPI MOSI), DIO_4 (SPI MISO) and DIO_5 (SPI SCLK).
The control signal are DIO_0 (move Left), DIO_7 (move right) and AIO_8 (Start and Fire).A
schematic for a connection board between a VM800B and a UMFT51-AA is included in the
Appendix. On an FT51A EVM the CN7 connector is used to interface with the VM800B module.
1.2 Features
The FT800 Spaced Invaders example has the following features:
-
Open source firmware.
Reads input from a controller using GPIO.
Displays graphics output on an FT800 enabled display via as SPI Master Interface.
1.3 Limitations
None specified
1.4 Scope
The guide is intended for developers who are creating applications, extending FTDI provided
applications or implementing example applications for the FT51A.
In the reference of the FT51A, an “application” refers to firmware that runs on the FT51A;
“libraries” are source code provided by FTDI to help user, access specific hardware features of the
chip.
The FT51A Tools are currently only available for Microsoft Windows platform and are tested on
Windows 7 and Windows 8.1.
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AN_349 FT51A FT800 Spaced Invaders Sample
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2 Firmware Overview
This section provides details on the libraries used to create the example project.
2.1 FT800 Display
The VM800B module interface for displaying the graphics and text is configured over the SPI
Master interface. Commands and da ta to send are stored in a buffer in RAM and sent in batches to
the FT800 device on the VM800B module regular intervals.
The firmware includes an FT800 abstraction layer providing functions which are used to perform
actions on the FT800. This layer is in the ft_gpu directory of the sample source code. The
definition of FT51A_PLATFORM and FT51A_PLATFORM_SPI in the file FT_Platform.h are used to enable
the FT51A abstraction in the libraries and use SPI for the communications. The same library can be
used for other FTDI microcontrollers.
2.2 FT51A Libraries
The firmware uses the SPI Master library, general config library and the IOMUX library. The IOMUX
library is used in the example code to set the output characteristics of the SPI Master interface
The firmware is designed for the FT51A EVM module and may be extended to use the LCD for
displaying some information. If so, then it will need the I 2C Master library added.
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AN_349 FT51A FT800 Spaced Invaders Sample
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D oc ument Reference N o.: FT _001128
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3 FT800 Spaced Invaders Firmware
The firmware included in the example code demonstrates displaying graphics on an FT800 display.
All control logic and screen drawing triggers are initiated by timers in the SpacedInvaders function
in spaced_invaders.c. This function contains a while loop that does not exit.
3.1 Timer
A timer is used to provide delays and time measurements for implementing polling intervals.
The first timer ms_timer is used to create general purpose delays, for instance implementing a
delay function.
There is an array called updateTimer which contains several timers which are refreshed each
millisecond. These are used for timing the movement of the graphics elements on the screen, i.e.
the invaders, bombs, saucers, blasters .
void ms_timer_interrupt(const uint8_t flags)
{
ft_uint8_t timer;
(void) flags; // Flags not currently used
if (ms_timer)
{
ms_timer--;
}
// refresh all update timers ...
for (timer = 0; timer < REFRESH_TOTAL; timer++)
{
if (updateTimer[timer])
{
updateTimer[timer]--;
}
}
// Reload the timer
TH0 = MSB(MICROSECONDS_TO_TIMER_TICKS(1000));
TL0 = LSB(MICROSECONDS_TO_TIMER_TICKS(1000));
}
void ms_timer_initialise(void)
{
// Register our own handler for interrupts from Timer 0
interrupts_register(ms_timer_interrupt, interrupts_timer0) ;
// Timer0 is controlled by TMOD bits 0 to 3, and TCON bits 4 to 5.
TMOD &= 0xF0; // Clear Timer0 bits
TMOD |= 0x01; // Put Timer0 in mode 1 (16 bit)
// Set the count-up value so that it rolls over to 0 after 1 millisecond.
TH0 = MSB(MICROSECONDS_TO_TIMER_TICKS(1000));
TL0 = LSB(MICROSECONDS_TO_TIMER_TICKS(1000));
TCON &= 0xCF; // Clear Timer0's Overflow and Run flags
TCON |= 0x10; // Start Timer0 (set its Run flag)
}
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AN_349 FT51A FT800 Spaced Invaders Sample
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3.2 Writing to FT800
Commands to the FT800 can either be s ent discretely to registers or to internal RAM in batches
when the display is being constantly updated by the firmware.
Both methods will enable the SPI Master to talk to the FT800 with the Slave Select 1 (SS1) line
going high before sending commands. The next stage is to send an address of the register or area
of RAM to be addressed in the FT800. The data for the register or RAM follows before SS1 is de asserted to signal the end of the transfer.
A discrete register change is performed using the FT800_Write08 or FT800_Write16 functions in
the file ft800_demo_board.c. These functions call the hardware abstraction layer functions to turn
on slave select and send the register commands before turning off slave select.
Batches of commands will be stored in a RAM buffer on the FT51A called Ft_CmdBuffer (the size
and therefore the end offset of this buffer are held in the variable Ft_CmdBuffer_Index). Helper
functions FT800_CmdBuffer_AddCmd and FT800_CmdBuffer_AddStr functions are available to abstract
the operation of the buffer.
When the batch is complete the commands are sent to the FT800 RAM using the
FT800_CmdBuffer_Send function. The size of Ft_CmdBuffer is 4 kB, allowing for a maximum display
list of 1024 commands (32 bits per command).
Instructions for an entire screen update can be stored in the buffer before being transmitted to the
FT800 at a fixed interval. The update is triggered when the timer_display value reaches zero at
this point all current sensor readings are formatted and graphics created for t he screen update.
This document does not deal with the FT800 commands used to render the graphics on the
display.
3.3 How the Game Works
The game elements are processed according to a rota each time the timer controlling the element
expires. This drives a state machine for each element determining how far it moves, what
interaction it has with other elements and what action to take.
Button presses are detected on the GPIO lines and move the player’s blaster accordingly.
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C learance N o.: FT DI# 4 3 0
4 Possible Improvements
The following improvements can be made in order to more closely match the original arcade
version of Space Invaders …
Award an extra life at 1500 points.
Change the speed of the last invader depending on direction (arcade version moved 2
pixels at a time when moving to the left and 3 pixels at a time when moving to the right).
Do not display saucer if there are eight or less invaders left alive.
Add sound for shots being fired, explosions, the saucer and finally the sound of the
invaders marching.
Add animation on the start screen (there are videos available of the original arcade Space
Invaders).
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5 Contact Information
Head Office – Glasgow, UK
Branch Office – Tigard, Oregon, USA
Future Technology Devices International Limited
Unit 1, 2 Seaward Place, Centurion Business Park
Glasgow G41 1HH
United Kingdom
Tel: +44 (0) 141 429 2777
Fax: +44 (0) 141 429 2758
Future Technology Devices International Limited
(USA)
7130 SW Fir Loop
Tigard, OR 97223-8160
USA
Tel: +1 (503) 547 0988
Fax: +1 (503) 547 0987
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
[email protected]
[email protected]
[email protected]
E-Mail (Sales)
E-Mail (Support)
E-Mail (General Enquiries)
[email protected]
[email protected]
[email protected]
Branch Office – Taipei, Taiwan
Branch Office – Shanghai, China
Future Technology Devices International Limited
(Taiwan)
2F, No. 516, Sec. 1, NeiHu Road
Taipei 114
Taiwan , R.O.C.
Tel: +886 (0) 2 8791 3570
Fax: +886 (0) 2 8791 3576
Future Technology Devices International Limited
(C hina)
Room 1103, No. 666 West Huaihai Road,
Shanghai, 200052
C hina
Tel: +86 21 62351596
Fax: +86 21 62351595
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
Web Site
http://ftdichip.com
Distributor and Sales Representatives
Please visit the Sales Network page of the FTDI Web site for the contact details of our distributor(s) and sales
representative(s) in your country.
Sys tem and equipment manufacturers and des igners are res ponsible to ens ure that their s ystems, and any Future T ec hnology
D evic es I nternational L td (FT DI) devices inc orporated in their s ystems, meet all applicable s afety, regulatory and s ystem - level
performanc e requirements. A ll application-related information in this document (including application des c riptions , s ugges ted
FT D I devic es and other materials ) is provided for referenc e only. While FT D I has taken c are to as s ure it is ac c urate, this
information is s ubject to c ustomer c onfirmation, and FT D I dis c laims al l liability for s ys tem des igns and for any applic ations
as s istance provided by FTD I. U se of FT DI devices in life s upport and/or s afety applications is entirely at the us er’s ris k, a nd the
us er agrees to defend, indemnify and hold harmles s FTDI from any and all damages , c laims , s uits or expens e res ulting from
s uc h us e. T his doc ument is s ubject to c hange without notic e. N o freedom to us e patents or other intellectual property rights is
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des c ribed in this doc ument, may be adapted or reproduc ed in any material or electronic form without the prior written c ons ent
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AN_349 FT51A FT800 Spaced Invaders Sample
V ers ion 1 .1
D oc ument Reference N o.: FT _001128
C learance N o.: FT DI# 4 3 0
Appendix A – References
Document References
FTDI MCU web page: http://www.ftdichip.com/MCU.html
USB Test and Measurement Class specification:
http://www.usb.org/developers/docs/devclass_docs/USBTMC_1_006a.zip
IVI Foundation: http://www.ivifoundation.org/
SCPI specification: http://www.ivifoundation.org/docs/scpi-99.pdf
USB Device Firmware Update Class specification:
http://www.usb.org/developers/docs/devclass_docs/DFU_1.1.pdf
FT800 datasheet
FT800 Series Programmers Guide
Acronyms and Abbreviations
Terms
Description
HID
Human Interface Device
MTP
Multiple Time Program – non-volatile memory used to store program code
on the FT51A.
SPI
Serial Peripheral Interface
USB
Universal Serial Bus
USB-IF
USB Implementers Forum
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AN_349 FT51A FT800 Spaced Invaders Sample
V ers ion 1 .1
D oc ument Reference N o.: FT _001128
C learance N o.: FT DI# 4 3 0
Appendix B – FT800 and Joystick Schematic
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AN_349 FT51A FT800 Spaced Invaders Sample
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D oc ument Reference N o.: FT _001128
C learance N o.: FT DI# 4 3 0
Appendix C – Revision History
Document Title:
AN_349 FT51A FT800 Spaced Invaders Sample
Document Reference No.:
FT_001128
Clearance No.:
FTDI# 430
Product Page:
http://www.ftdichip.com/FTProducts.htm
Document Feedback:
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Revision
Changes
Date
1.0
Initial Release
2014-12-12
1.1
Update FT51 references to FT51A
2015-11-26
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