VS1033 Datasheet, PDF (61/70 Pages) List of Unclassifed Manufacturers – MP3/AAC/WMA/MIDI AUDIO CODEC

VLSI
Solution ^y
VS1033a PRELIMINARY
VS1033A
10. VS1033 REGISTERS
10.11.6 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 the data in the receiver is moved to the reveive
data register, the stop bit state is checked (logic high = ok, logic low = framing error) for status bit[4],
the RX INTR interrupt is sent, 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 0.6, 2005-01-05
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