Asynchronous Serial Ports (UARTs)
Am186™CC/CH/CU Microcontrollers User’s Manual
13-19
HSPABx registers, which is not programmed in the ABDIV field for one of the HSPABx
registers, is unattainable for that system.
In example B, the HSPAB0 register is not being used. The value of the ABDIV field for
HSPAB3 is greater than the ABTHRSH field for that register. Although this is not the case
for most systems, it is possible for the replacement divisor to fall outside of the range of
sampled baud rates that generate that divisor.
13.5.6
Interrupt Sources
All UART and High-Speed UART interrupt sources require two interrupt enable bits to be
set before that source is enabled to generate interrupts.
The first level consists of three main interrupt enable bits in the (H)SPCON0 control register.
The Receive Interrupt Enable (RXIE) bit enables interrupts that indicate receive data is
available (the RDR bit in the status register is 1). The Receive Status Interrupt Enable
(RSIE) bit enables interrupts on the condition or status of the received data. The Transmit
Interrupt Enable (TXIE) bit enables interrupts based on the status of the transmit data
(whether the TEMT bit in the status register is 0 or 1).
The (H)SPIMSK register contains the second-level interrupt bits. Even if these bits are set
to 1, interrupts are disabled if the corresponding first-level enable bit is not also set to 1.
Table 13-5 shows the interrupt sources for the UARTs. All first-level enable bits default to
Off (0). The defaults for the second-level bits vary and are listed.
Note that when a receive status bit has generated an interrupt condition and extended reads
are disabled, receive DMA requests are inhibited.
Table 13-5
UARTs Interrupt Sources
Interrupt Enable
1
Notes:
1. When the FIFOs are in use, High-Speed UART RDR and THRE should be disabled from generating interrupts.
When using the FIFOs, High-Speed UART RTHRSH is the logical replacement for RDR, and TTHRSH is the logical
replacement for THRE.
(H)SPCON0
1st-Level Enable
Bit (Default)
(H)SPIMSK
2nd-Level Enable
Bit (Default)
Receive data ready
RXIE (Off)
RDR (On)
Receive FIFO threshold reached
RXIE (Off)
RTHRSH (Off)
Overrun error on receive FIFO
RSIE (Off)
OERIM (Off)
Transmit holding register empty
TXIE (Off)
THRE (On)
Transmit FIFO threshold reached
TXIE (Off)
TTHRSH (Off)
Transmitter empty, transmit FIFO empty on High-Speed UART
TXIE (Off)
TEMT (Off)
Parity error
RSIE (Off)
PER (On)
Overrun error
RSIE (Off)
OER (On)
Framing error
RSIE (Off)
FER (On)
Break detected
RSIE (Off)
BRK (On)
Address bit set on receive
RSIE (Off)
AB (Off)
Character match on receive
RSIE (Off)
MATCH (Off)
Receive line idle detected
RXIE (Off)
IDLED (Off)
Receive line idle
RSIE (Off)
IDLE (Off)
Summary of Contents for Am186 CC
Page 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Page 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Page 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Page 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Page 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Page 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Page 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Page 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Page 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...