Z8FMC16100 Series Flash MCU
Product Specification
119
Data Field
Idle State
of Line
Stop Bit(s)
msb
lsb
1
0
Start
Bit 0
Bit 1
Bit 2
Bit 3 Bit 4
Bit 5
Bit 6
Bit 7
MP
1
2
Figure 15. LIN-UART Asynchronous Multiprocessor Mode Data Format
In Multiprocessor (9-bit) mode, the Parity bit location (9th bit) becomes the MULTIPRO-
CESSOR control bit. The LIN-UART Control 1 and Status 1 registers provide MULTI-
PROCESSOR (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.
Multiprocessor Mode Receive Interrupts
When MULTIPROCESSOR (9-bit) mode is enabled, the LIN-UART processes only
frames addressed to it. The determination of 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 does not need 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 MPENof the LIN-UART Control 1 Register must be set to 1.
The first scheme is enabled by writing 01bto 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 that 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 MPRXbit of the LIN-UART Status 1 Register for each incoming byte. If
MPRX=1, a new frame has begun. 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 interrupts to go inactive until the next address byte. If the new frame’s address
matches the LIN-UART’s, then the data in the new frame is processed as well.
PS024604-1005
P R E L I M I N A R Y
Multiprocessor Mode
ZILOG [ ZILOG, INC. ]
