VS1103B Datasheet, PDF (53/61 Pages) List of Unclassifed Manufacturers – MIDI/ADPCM AUDIO CODEC

VLSI
Solution ^y
VS1103b
VS1103B
8. VS1103B REGISTERS
8.11.6 Interrupts and Operation
Transmitter operates as follows: After an 8-bit word is written to the transmit data register it will be
transmitted instantly if the transmitter is not busy transmitting the previous byte. When the transmission
begins a TX INTR interrupt will be sent. Status bit [1] informs the transmitter data register empty (or
full state) and bit [0] informs the transmitter (shift register) empty state. A new word must not be written
to transmitter data register if it is not empty (bit [1] = ’0’). The transmitter data register will be empty
as soon as it is shifted to transmitter and the transmission is begun. It is safe to write a new word to
transmitter data register every time a transmit interrupt is generated.
Receiver operates as follows: It samples the RX signal line and if it detects a high to low transition, a
start bit is found. After this it samples each 8 bit at the middle of the bit time (using a constant timer),
and fills the receiver (shift register) LSB first. Finally if a stop bit (logic high) is detected the data in
the receiver is moved to the reveive data register and the RX INTR interrupt is sent and a status bit[2]
(receive data register full) is set, and status bit[2] old state is copied to bit[3] (receive data overrun). After
that the receiver returns to idle state to wait for a new start bit. Status bit[2] is zeroed when the receiver
data register is read.
RS232 communication speed is set using two clock dividers. The base clock is the processor master
clock. Bits 15-8 in these registers are for first divider and bits 7-0 for second divider. RX sample
frequency is the clock frequency that is input for the second divider.
Version 1.01, 2007-09-03
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