After the SLOT16 bit is set, all subsequent packets are standardized to 16 bits.
Once the data is aligned, the EPROM's monitor POST routine then writes and verifies three
patterns to an internal register in the codec. If all three writes are verified, the codec
connection is verified. The ADSP-21065L then continually transmits and receives data
from the codec. Slot 0 in each transmission specifies which slots contain valid data (and
are called the Tag Phase time slot).
3.3.3.1
Linking Your Code to the RS-232 Monitor Codec
Interrupt Handlers
To use the EPROM monitor’s interrupt handler for the AD1819, the user needs
to use one of the following methods:
C-code—link your code with the file demorth.asm (this is located in the
...\demos\tt folder). This file contains a replacement for the standard C runtime
header 060_hdr.asm. This file also includes a jump to the EPROM codec
interrupt handler at the SPORT1 Tx interrupt vector location.
Assembly—use the demorth.asm file as the interrupt vector table or create your
own interrupt vector table that includes a jump to address 0x9001at the SPORT1
Tx interrupt vector location.
3.3.3.2 Linking Your Code to the RS-232 Monitor DMA Buffers
The monitor constantly sends and receives packets from the codec. To send
data to the codec, the user needs to put the desired data into the codec transmit
buffer, and set the transmit variable. Similarly, to receive data from the codec,
the receive variable should be set to a value > 0. The variable may then be
polled for the change back to 0. When this happens codec data has been
transferred into the codec receive buffer, and may be read.
Figure 3-1 shows the software structure of the codec data transfer. The transfer
is set up by the RS232 monitor program via EPROM boot.
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