Z8F1680SH020SG Datasheet, PDF (177/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
152
Figure 23. LIN-UART Asynchronous MULTIPROCESSOR Mode Data Format
In MULTIPROCESSOR (9-bit) Mode, the Parity bit location (9^th bit) becomes the
Multiprocessor control bit. The LIN-UART Control 1 and Status 1 registers provide MUL-
TIPROCESSOR (9-bit) Mode control and status information. If an automatic address
matching scheme is enabled, the LIN-UART Address Compare register holds the network
address of the device.
12.1.9.1. MULTIPROCESSOR Mode Receive Interrupts
When MULTIPROCESSOR (9-bit) Mode is enabled, the LIN-UART processes only
frames addressed to it. To determine whether a frame of data is addressed to the LIN-
UART can be made in hardware, software or a combination of the two, depending on the
multiprocessor configuration bits. In general, the address compare feature reduces the load
on the CPU, because it is not required to access the LIN-UART when it receives data
directed to other devices on the multinode network. The following three MULTIPROCES-
SOR Modes are available in hardware:
• Interrupt on all address bytes
• Interrupt on matched address bytes and correctly framed data bytes
• Interrupt only on correctly framed data bytes
These modes are selected with MPMD[1:0] in the LIN-UART Control 1 Register. For all
MULTIPROCESSOR Modes, bit MPEN of the LIN-UART Control 1 Register must be set
to 1.
The first scheme is enabled by writing 01b to MPMD[1:0]. In this mode, all incoming
address bytes cause an interrupt, while data bytes never cause an interrupt. The interrupt
service routine checks the address byte which triggered the interrupt. If it matches the
LIN-UART address, the software clears MPMD[0]. At this point, each new incoming byte
interrupts the CPU. The software determines the end of the frame and checks for it by
reading the MPRX bit of the LIN-UART Status 1 Register for each incoming byte. If
MPRX = 1, a new frame begins. If the address of this new frame is different from the LIN-
UART’s address, then MPMD[0] must be set to 1 by software, causing the LIN-UART
PS025015-1212
PRELIMINARY
LIN-UART