IA186EM_04 Datasheet, PDF (23/133 Pages) InnovASIC, Inc – 8/16-Bit Microcontrollers

IA186EM/IA188EM
8/16-BIT Microcontrollers
Data Sheet
As of Production Version -03
SPRD (086h) - Serial Port Receive Data Register.
Data received over the serial port are stored in this register until read. The data are received initially by
the receive shift register (no software access) permitting data to be received while the previous data are
being read.
The RDR bit (Receive Data Ready) in the serial port status register indicates the status of the SPRD
register. Setting the RDR bit 1 indicates that there is valid data in the receive register.
The value of the SPRD register is undefined at reset.
15 14
13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
RDATA
Reserved (bits 15-8) – Reserved.
RDATA [7:0] (bits 7-0) – Holds valid data while the RDR bit of the status register is set.
SPTD (084h) - Serial Port Transmit Data Register.
Data is written to this register by software, with the values to be transmitted by the serial port. Double
buffering of the transmitter allows for the transmission of data from the transmit shift register (no
software access), while the next data are written into the transmit register.
The THRE bit in the Serial Port Status register indicates whether there is valid data in the SPDT register.
The THRE bit must be a 1 before writing data to this register to prevent overwriting valid data that is
already in the SPDT register.
The value of the SPTD register is undefined at reset.
15 14
13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
TDATA
Reserved (bits 15-8) – Reserved.
TDATA [7:0] (bits 7-0) – Holds the data to be transmitted.
SPSTS (082h) – Serial Port STatuS Register.
This register stores information concerning the current status of the port. The status bits are described
below.
The value of the SPSTS register is undefined at reset.
15 14 13 12 11 10 9 8 7 6
5
43
2 10
Reserved
TEMT THRE RDR BRKI FER PER OER
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