This application note describes the interface between Motorola's
M68HC05 Family of microcontrollers and Motorola's MC145051 analogto-
digital converter (ADC). The MC145051 is a 10-bit, 11-channel, serial
interface ADC. The microcontroller unit (MCU) interface must be able to
"talk" to the MC145051 using a serial communication link. One of the
most popular hardware modules available in the M68HC05 Family is the
serial peripheral interface (SPI). This application note provides the
hardware and software design to link the SPI module on the
MC68HC705C8 MCU to the MC145051.
Not all M68HC05 Family members have SPI modules. An M68HC05
MCU without an SPI must interface to the MC145051 using a software
driver. This method "bit bangs" a port of the MCU to communicate with
the MC145051. Although not as efficient as the hardware SPI method, it
provides MCUs without an SPI a means to retrieve data from the
MC145051. This application note will utilize the MC68HC705K1 MCU to
demonstrate the software driver routine.