Z86230 Datasheet, PDF (20/61 Pages) Zilog, Inc. – ADVANCED VIOLENCE BLOCKING AND NTSC 21 XDS

SERIAL COMMUNICATIONS INTERFACE
I²C BUS OPERATION
FIGURE 4. I²C BUS WRITE (COMMAND)
I²C One-Byte WRITE (Command)
START
SLAVE ADDR
WRITE CMD
STOP
(WRITE=28h for the 1^st I²C Address and 2Ah for the 2^nd I²C Address)
I²C Two-Byte WRITE (Command & Data)
START
SLAVE ADDR
WRITE CMD
WRITE DATA
STOP
(WRITE=28h for the 1^st I²C Address and 2Ah for the 2^nd I²C Address)
NOTE: The Status Register RDY bit must be read and checked prior to the START
condition of either WRITE sequence above. Refer to the One Byte READ (Status Only)
in Figure 5 for more information on reading the Status Register.
4.1.4 Reading Data Using the I²C Bus
The Z86230 I²C bus supports READ sequences up to 34 bytes in length. All READ
sequences output the Serial Status Register (SSR) as the first output byte. The data
to be read is selected by sending the READ BANK SELECT (RBS) command. Four
READ bank modes are available in the Z86230:
TABLE 5. Z86230 I²C READ BANK SELECT (RBS) COMMAND
RBS
Command
Descriptions
Bank 0
Bank 1
A general-purpose bank used to read the Z86230-defined internal registers. The
register to be read from Bank 0 is set up manually using the READ SELECT
commands, RDS1 and RDS2. These commands load the selected data byte (or pair
of bytes) into the first location(s) of Bank 0, and set the DAV bit to indicate the
availability of data.
A special purpose bank provided to facilitate the reading of commonly accessed
data. This bank contains the Program Blocking registers and permits direct,
multibyte reading of internal registers 08h through 11h. These registers are
described in the internal register section. When it is selected, the sequence of bytes
read is SSR, followed by internal registers 08h, 09h, 0Ah, 0Bh, 0Ch, 0Dh, 0Eh, 0Fh,
10h, and 11h.
Bank 2
A special purpose bank provided to facilitate the reading of commonly accessed
data. This bank contains the XDS Program Name data from the most recently
received current class type 3 packet.
Bank 3
A special purpose bank provided to facilitate the reading of commonly accessed
data. This bank contains the XDS Network Name and Call Letter data. The first 26
bytes has the XDS Network Name from the most recently received XDS channel
class type 1 packet. Bytes 26 through 31 has the XDS Call Letters data from the
most recently received XDS channel class type 2 packet
NOTE: Banks 2 and 3 are 33 bytes in length. Byte 32 of these banks contains an 8 bit checksum. The checksum
is calculated such that the addition of the 32 data bytes and the checksum modulo 256 equals zero. The
checksum should always be evaluated after reading this data to ensure that the XDS data is not being updated
during the READ operation. The result is a meaningless combination of two unrelated XDS data packets. If a
bad checksum is encountered, the READ operation should be repeated.
20
Z86230—PRELIMINARY
PS000400-TVC0499