Datasheet

Data Sheet ADuC7019/20/21/22/24/25/26/27/28/29
Rev. F | Page 73 of 104
Table 108. COMSTA1 Register
Name Address Default Value Access
COMSTA1 0xFFFF0718 0x00 R
COMSTA1 is a modem status register.
Table 109. COMSTA1 MMR Bit Descriptions
Bit Name Description
7 DCD Data carrier detect.
6 RI Ring indicator.
5
DSR
Data set ready.
4 CTS Clear to send.
3 DDCD Delta DCD. Set automatically if DCD changed
state since last COMSTA1 read. Cleared automati-
cally by reading COMSTA1.
2 TERI Trailing edge RI. Set if RI changed from 0 to 1
since COMSTA1 was last read. Cleared
automatically by reading COMSTA1.
1 DDSR Delta DSR. Set automatically if DSR changed state
since COMSTA1 was last read. Cleared
automatically by reading COMSTA1.
0 DCTS Delta CTS. Set automatically if CTS changed state
since COMSTA1 was last read. Cleared
automatically by reading COMSTA1.
Table 110. COMSCR Register
Name Address Default Value Access
COMSCR 0xFFFF071C 0x00 R/W
COMSCR is an 8-bit scratch register used for temporary
storage. It is also used in network addressable UART mode.
Table 111. COMDIV2 Register
Name
Address
Default Value
Access
COMDIV2 0xFFFF072C 0x0000 R/W
COMDIV2 is a 16-bit fractional baud divide register.
Table 112. COMDIV2 MMR Bit Descriptions
Bit Name Description
15 FBEN Fractional baud rate generator enable bit.
Set by user to enable the fractional baud
rate generator. Cleared by user to generate
baud rate using the standard 450 UART
baud rate generator.
14:13
Reserved.
12:11 FBM[1:0] M if FBM = 0, M = 4 (see the Fractional
Divider section).
10:0 FBN[10:0] N (see the Fractional Divider section).
Network Addressable UART Mode
This mode connects the MicroConverter to a 256-node serial
network, either as a hardware single master or via software in a
multimaster network. Bit 7 (ENAM) of the COMIEN1 register
must be set to enable UART in network addressable mode (see
Table 114). Note that there is no parity check in this mode.
Network Addressable UART Register Definitions
Four additional registers, COMIEN0, COMIEN1, COMIID1, and
COMADR are used in network addressable UART mode only.
In network address mode, the least significant bit of the COMIEN1
register is the transmitted network address control bit. If set to
1, the device is transmitting an address. If cleared to 0, the
device is transmitting data. For example, the following master-
based code transmits the slave’s address followed by the data:
COMIEN1 = 0xE7; //Setting ENAM,
E9BT, E9BR, ETD, NABP
COMTX = 0xA0; // Slave address is 0xA0
while(!(0x020==(COMSTA0 & 0x020))){} //
wait for adr tx to finish.
COMIEN1 = 0xE6; // Clear NAB bit
to indicate Data is coming
COMTX = 0x55; // Tx data to slave: 0x55
Table 113. COMIEN1 Register
Name Address Default Value Access
COMIEN1 0xFFFF0720 0x04 R/W
COMIEN1 is an 8-bit network enable register.
Table 114. COMIEN1 MMR Bit Descriptions
Bit Name Description
7 ENAM Network address mode enable bit. Set by user to
enable network address mode. Cleared by user to
disable network address mode.
6
E9BT
9-bit transmit enable bit. Set by user to enable
9-bit transmit. ENAM must be set. Cleared by user
to disable 9-bit transmit.
5 E9BR 9-bit receive enable bit. Set by user to enable
9-bit receive. ENAM must be set. Cleared by user
to disable 9-bit receive.
4 ENI Network interrupt enable bit.
3 E9BD Word length. Set for 9-bit data. E9BT has to be
cleared. Cleared for 8-bit data.
2 ETD Transmitter pin driver enable bit. Set by user to
enable SOUT pin as an output in slave mode or
multimaster mode. Cleared by user; SOUT is
three-state.
1 NABP Network address bit. Interrupt polarity bit.
0 NAB Network address bit (if NABP = 1). Set by user to
transmit the slave address. Cleared by user to
transmit data.
Table 115. COMIID1 Register
Name Address Default Value Access
COMIID1 0xFFFF0724 0x01 R
COMIID1 is an 8-bit network interrupt register. Bit 7 to Bit 4
are reserved (see Table 116).