ez80190 ZiLOG Semiconductor, ez80190 Datasheet - Page 163

• Manufacturer Part Number: ez80190
• Description: Ez80190 Microprocessor
• Manufacturer: ZiLOG Semiconductor

eZ80190 Product Specification
149
ZDI Single-Bit Byte Separator
Following each 8-bit ZDI data transfer, a single-bit byte separator is used. The
th
ZDA pin should be forced High (1) prior to the ZCL rising edge for this 9
bit. For
most ZDI operations, the ZDI register address automatically increments during
this single-bit byte separator period. The same read or write operation as just
completed can then be immediately performed on the next ZDI register. If a differ-
ent operation or register address is required, a ZDI START signal during the byte
separator bit can be used to terminate the previous read or write operation and
signify initiation of a new ZDI register operation.
ZDI Register Addressing
Following a START signal, the ZDI master must output the ZDI register address.
All data transfers with the ZDI block use special ZDI registers. The ZDI control
registers that reside in the ZDI register address space should not be confused
with the eZ80190 device peripheral registers that reside in the I/O addressing
space of the eZ80190 device.
Many locations in the ZDI control register address space are shared by two regis-
ters, one for Read Only access and one for Write Only access. As an example, a
read from ZDI register address
returns the Product ID Low Byte while a write
00h
to this same location,
, stores the Low byte of one of the address match values
00h
used for generating break points.
The format for a ZDI address is seven bits of address, followed by one bit for read
or write control, and completed by a single-bit byte separator in which ZDA must
be 1. The data separator time period is used to allow the ZDI master to send a
new ZDI START signal, if necessary. The ZDI executes a read or write operation
depending on the state of the R/W bit (0 = write, 1 = read).
Figure 30
illustrates the
timing for address writes to ZDI registers.
PS006613-0306
PRELIMINARY
ZiLOG Debug Interface