Chapter 8 - Memory and Sound

Abstract

This chapter explores the internal memory of the Programmable Interface Controllers (PIC) and the access to external memory. The memory referred to is Electrically Erasable Programmable Read Only Memory (EEPROM). This memory stores information or data even after the power is disconnected. It can be changed at anytime within a program, but once the PIC is shutdown anything in EEPROM is not erased. All flash memory PICs have internal EEPROM memory, but usually less than lk. If more than lk is needed, then external EEPROM memory chips are used. Access to the internal EEPROM is quite easy in PicBasic by using a single WRITE or READ command. Many external memory chips communicate using the Phillips I2c protocol. PicBasic makes that easy with the I2CIN and I2COUT commands. The projects (Using Internal Memory and Accessing External Memory) illustrated in this chapter show how to access the internal EEPROM memory and external memory. The third project (Making Music) illustrated shows how the PIC is converted into a music generator by playing music through a speaker using the SOUND command.