UG-1262
Rev. B | Page 260 of 312
REGISTER DETAILS: UART
TRANSMIT HOLDING REGISTER
Address: 0x40005000, Reset: 0x0000, Name: COMTX
COMRX and COMTX share the same address although they are implemented as different registers. If these registers are written to, the
user accesses the transmit holding register (COMTX). If these registers are read from, the user accesses the receive buffer register (COMRX).
Table 321. Bit Descriptions for COMTX
Bits Bit
Name
Settings
Description
Reset Access
[15:8] Reserved
Reserved.
0x0 R
[7:0] THR
Transmit Holding Register. This is an 8-bit register to which the user can write the data
to be sent. If COMIEN, Bit 1 is set, an interrupt generates when COMTX is empty. If user
code sets COMIEN, Bit 1 when COMTX is already empty, an interrupt generates immediately.
0x0 W
RECEIVE BUFFER REGISTER
Address: 0x40005000, Reset: 0x0000, Name: COMRX
Table 322. Bit Descriptions for COMRX
Bits Bit
Name
Settings
Description
Reset Access
[15:8] Reserved
Reserved.
0x0 R
[7:0] RBR
Receive Buffer Register. This is an 8-bit register from which the user can read received
data. If COMIEN, Bit 0 is set, an interrupt generates when this register is fully loaded with
the received data via the serial input port. If user code sets the COMIEN, Bit 0 while
COMRX is full, an interrupt generates immediately.
0x0 R
INTERRUPT ENABLE REGISTER
Address: 0x40005004, Reset: 0x0000, Name: COMIEN
COMIEN is the interrupt enable register that configures which interrupt source generates the interrupt. Only the lowest four bits in this register
enable interrupts. Bit 4 and Bit 5 enable UART DMA signals. The UART DMA channel and interrupt must be configured in the DMA block.
Table 323. Bit Descriptions for COMIEN
Bits Bit
Name Settings
Description
Reset
Access
[15:6] Reserved
Reserved.
0x0 R
5
EDMAR
DMA Requests in Receive Mode.
0x0
R/W
0
DMA requests disabled.
1
DMA requests enabled.
4
EDMAT
DMA Requests in Transmit Mode.
0x0
R/W
0
DMA requests are disabled.
1
DMA requests are enabled.
3
EDSSI
Modem Status Interrupt. Interrupt is generated when COMMSR, Bits[3:0] is set.
0x0
R/W
0
Interrupt
disabled.
1
Interrupt
enabled.
2
ELSI
Receive Status Interrupt.
0x0
R/W
0
Interrupt
disabled.
1
Interrupt
enabled.
1
ETBEI
Transmit Buffer Empty Interrupt.
0x0
R/W
0
Interrupt
disabled.
1
Interrupt
enabled.
0
ERBFI
Receive Buffer Full Interrupt.
0x0
R/W
0
Interrupt
disabled.
1
Interrupt
enabled.