After the ARM mini-board for LPC2148 is created, it’s time to develop a development board. I want to make the board as universal as possible.So I decided to put I2C, SPI, COM, and JTAG on board. I decided to use an external voltage adapter as there are needed 5V and 3.3V DC sources. For my experiments, I can use those voltages straight from a PC source. 5V there is used to supply MAX232IC. I decided to use it instead of MAX3232 because it is easier to get them in the market. Of course, I left the ability to use and MAX3232 by changing the jumper. All other free pins I made accessible by adding pinheads inboard.
One day I’ve got an ARM LPC2148 chip in my hands. The Philips LPC2148 is an ARM7TDMI-S based high-performance 32-bit RISC Microcontroller with Thumb extensions 512KB on-chip Flash ROM with In-System Programming (ISP) and In-Application Programming (IAP), 32KB RAM, Vectored Interrupt Controller, Two 10bit ADCs with 14 channels, USB 2.0 Full Speed Device Controller, Two UARTs, one with full modem interface. Two I2C serial interfaces, Two SPI serial interfaces, Two 32-bit timers, Watchdog Timer, a PWM unit, Real-Time Clock with optional battery backup, Brown-out detect circuit General purpose I/O pins. CPU clock up to 60 MHz, On-chip crystal oscillator, and On-chip PLL.