MSP53C691 Interface Overview
2-2
2.1
MSP53C691 Interface Overview
The MSP53C691 interfaces with the master microcontroller either in 4-bit or
in 8-bit mode.
The MSP53C691 and the master microcontroller transfer data across four
(DATA0–DATA3) or eight (DATA0–DATA7) data lines, depending upon which
mode the slave is in.
In either mode the transfer of data is controlled by the two control lines: R/W
and STROBE. When the MSP53C691 is ready to receive data from the
microcontroller, it sets INRDY low. The microcontroller sends data to the
MSP53C691 by setting R/W low and then pulsing STROBE high-low-high. The
MSP53C691 latches the data at the rising edge of the STROBE pulse. The
MSP53C691 also sets INRDY high at the rising edge of the STROBE pulse.
Setting INRDY high indicates that the MSP53C691 is not ready to receive any
more data.
When the MSP53C691 is ready to send data to the microcontroller, the
MSP53C691 sets OUTRDY low. The microcontroller responds by setting R/W
high and then pulsing STROBE high-low-high. (The microcontroller latches
the data while STROBE is low.) This informs the slave that the data has been
written to the microcontroller. The MSP53C691 sets OUTRDY high at the ris-
ing edge of the STROBE pulse. Setting OUTRDY high indicates that the
MSP53C691 does not have data ready to send.
Both 4-bit and 8-bit modes are controlled by commands sent to the slave. A
separate bit (DATA 4) is used in 4-bit mode to differentiate between the speech
data or command sent to the slave. This line is referred to as data/command
line. This is discussed in detail in the software overview section.
Summary of Contents for MSP53C691
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