Specifications

 4 Kbytes Flash Program Memory for storing and executing application

code

 512 Bytes RAM data memory

The microcontroller is also capable of up to 16 MIPS (Millions of Instructions Per

Second), which is standard for a microcontroller of this size and power. The

microcontroller is optimized to be programmed in the C language, the preferred

programming language of the group. The secondary microcontroller will be

responsible for taking in the data from the SHT21 sensor. The 16-bit wide data

path will be sufficient for process the temperature and humidity data, and then

passing the information along to the main microcontroller via the 802.15.4 ZigBee

device.

The internal flash program memory for a device is used for storing and executing

application code. The 4 Kbytes of Flash memory will hold our programming

code, and allow the program to be modified in the future should more features be

added to the system. The memory is readable, writable and erasable when

operating with a VDD over 1.8V. 512 Bytes of RAM will allow is low data rate RF

module to run quickly and effectively.

The secondary microcontroller has 18 I/O pins that can be programmed to work

with other devices such as the sensor and the ZigBee RF transceiver. This

number of I/O pins is above the required number for our design, in case

expansion of the system is needed. The microcontroller also has ADC modules

to transfer input analog voltages into a digital number proportional to the input

voltage or current.

I/O Characteristics:

 18 Input/ Output (I/O) pins

 Analog-to-Digital Converters

 10-bit A/D Convert

 9 Analog-to-Digital (ADC) input channels

The SPI module protocol will interface the secondary microcontroller with the

ZigBee wireless chip. The I2C™ module protocol will be used to interface the

temperature and relative humidity sensor with the PIC24F04KA201

microcontroller. The I2C™ module supports both Master and Slave modes of

operation, useful for the sensor connection. The secondary microcontroller block

diagram in Figure 9 below illustrates the peripheral connection with the different

components.

Three Serial Communication Peripherals:

 1 – SPI module

 1 – I2C™ module

 1 – UART module