MB90420G/425G Series
50
10. UART
The UART is a general purpose serial data communication interface for synchronous communication, or asyn-
chronous (start-stop synchronized) communication with external devices. Functions include normal bi-directional
functions, as well as master/slave type communication functions (multi-processor mode : master side only
supported) .
(1) UART Functions
The UART is a general purpose serial data communication interface for sending and receiving of serial data with
other CPU’s or peripheral devices, and provides the following functions.
Note : The UART in clock synchronous transfer does not add start bits or stop bits, but transfers data only.
: Setting not available
*1 : “
+” indicates an address/data selection bit (A/D) for communication control.
*2 : In receiving only one stop bit is detected.
Functions
Data buffer
Full duplex double buffer
Transfer modes
Clock synchronous (no start/stop bits)
Clock asynchronous (start-stop synchronized)
Baud rate
Exclusive baud rate generator provides a selection of 8 rates
External clock input enabled
Internal clock (can use internal clock feed from 16-bit reload timer)
Data length
7-bit (asynchronous normal mode only)
8-bit
Signal type
NRZ (Non return to zero)
Receiving error detection
Framing errors
Overrun errors
Parity errors (not enabled in multiprocessor mode)
Interrupt request
Receiving interrupt (receiving completed, receiving error detection)
Sending interrupt (sending completed)
Sending/receiving both compatible with expanded intelligent I/O services
(EI2OS)
Master/slave type
communication function
(multi-processor mode)
1 (master) -to-n (slave) communication enabled (only master side supported) .
Operating mode
Data length
Synchronization
Stop bit length
No parity
Parity
0
Normal mode
7-bit or 8-bit
Asynchronous
1-bit or 2-bit *2
1
Multi-processor mode
8
+ 1 *1
Asynchronous
2Normal mode
8
Synchronous
None