Multichannel Serial Interfaces
9-30
Word Size
To choose the size of the word, set its size minus one into the main parameters
registers.
Control bit:
MAIN_PARAMETERS_REG(3:0) = WORD_ SIZE
(2
<=
WORD_ SIZE
<=
15)
The MCSI transmits and receives the most significant bit first. For example,
if the word_size equals 11, the upper 12 bits of the TX registers are transmitted,
the upper 12 bits of the RX registers contain the received data, and the lower
4 bits are zeros.
Frame Size
To add any overhead bits at the end of each frame, set the number of desired
overhead bits in the over_size_register.
Control bit:
OVER_CLOCK_REG(9:0) = OVER_CLK (0
<=
OVER_CLK
<=
1023)
Transmission Clock Frequency
In master mode, the clock frequency is derived from the 12-MHz master clock
and can be programmed from 5.8 kHz to 6 MHz in increments of 83 ns.
Control bit:
CLOCK_FREQUENCY_REG(10:0) = CLK_FREQ
(2
<=
CLK_FREQ
<=
2047)
with
(t
CLK
= t
12MHz
* CLK_FREQ)
9.5.1.2
Sample Setup for Communication
µ
-Law Interface Using Interrupts
MCSI Configuration
An example of communication
µ
-law interface setup using interrupts follows.
-
DSP_Write(0x0000) = CONTROL_REG (disable MCSI for setup)