The LPC2418 ARM7 is a 32-bit processor running at speeds of up to 60Mhz.(1) This is roughly equivalent to the processor used in the original Playstation.(2) The LPC has about twice the clock speed as the Playstation when running at full power, but considering the LPC's application in a portable game system running off a battery, the processor will likely be running at or below Playstation speeds.
A 32-bit processor running at Playstation speeds may seem like overkill for a simple game like Pac-Man. It is overpowered for the game. In designing this system, the student was designing hardware that could run a variety of games. In the future the student would like to continue programming games that are too complex to be programmed in the short time frame of the project.
Besides speed the LPC 2418 has many other features as outlined by the Keil parts database website.
Of the many systems on the chip, The SPI, USB 2.0 interface, the ADC, and the 32 bit timers are of the most interest to this project.
The SPI (Serial Peripheral Interface) will be the tool used to connect to and communicate with the LCD screen. The SPI works by sending data serially that is synchronized with a clock. Although the LPC2418 has two SPI systems, only one SPI is available on the output pins on the Logomatic V2. This should not be an obstacle to this project. The two pins from the SPI system that will be used are the SCK1 (SCK) and the MOSI1 (MOSI). SCK sets the speed of the data transfer. The speed of SCK depends on the speed of the
VPB Clock and the SPCCR register. The VPBDIV register value that sets the speed of the VPB Clock by dividing the C Clock by the value in VPBDIV. The speed of the VPB Clock is further divided by the value in the SPCCR register. A frequency of 1MHz on the SCK should be sufficient. Another register of note is the SPCR register which sets the SPI to a master or slave mode. When interfacing with the screen the SPI should be the master and the SPCR register should have a value of 0x20. The SPI will be discussed more in the software section The Nokia 6100 Display Driver