DAN-139 Datasheet, PDF (3/5 Pages) Exar Corporation – EXAR’S XR16L580 COMPARED

DATA COMMUNICATIONS APPLICATION NOTE
DAN139
1.3 FIRMWARE DIFFERENCES BETWEEN THE XR16L580 AND INDUSTRY STANDARD 16550
The internal registers in the XR16L580 and 16550 are similar with some exceptions:
TABLE 2: XR16L580 AND 16550 REGISTER SET DIFFERENCES
A2:A0 R/W
LCR Bit-7 = 0
001 R/W
010
W
XR16L580
Interrupt Enable Register (IER)
• Bit-7 = Auto CTS# Interrupt Enable
• Bit-6 = Auto RTS# Interrupt Enable
• Bit-5 = Xoff Interrupt Enable
• Bit-4 = Sleep Mode Enable
FIFO Control Register (FCR)
• Bit-5 = TX FIFO Trigger Level Select Bit-1
• Bit-4 = TX FIFO Trigger Level Select Bit-0
STANDARD 16550
Interrupt Enable Register (IER)
• Bit-7 = Not Used
• Bit-6 = Not Used
• Bit-5 = Not Used
• Bit-4 = Not Used
FIFO Control Register (FCR)
• Bit-5 = Not Used
• Bit-4 = Not Used
010
R
100 R/W
LCR = 0xBF
010 R/W
100 R/W
101 R/W
110 R/W
111 R/W
Interrupt Status Register (ISR)
• Bit-5 = RTS/CTS Interrupt
• Bit-4 = Xoff or Special Character Interrupt
Interrupt Status Register (ISR)
• Bit-5 = Not Used
• Bit-4 = Not Used
Modem Control Register (MCR)
• Bit-7 = BRG Prescaler Select
• Bit-6 = IR Mode Enable
Modem Control Register (MCR)
• Bit-7 = Not Used
• Bit-6 = Not Used
• Bit-5 = Xon any (while in Xoff state, start trans- • Bit-5 = Not Used
mission upon receiving any character)
• Bit-2 = control OP1 output
• Bit-2 = control OP1 output (in internal loopback
mode only) / Invert Infrared RX signal polarity (if
EFR bit-4 = 1)
Enhanced Feature Register (EFR)
N/A
• Auto RTS/CTS Enable, Enhanced Functions
Enable, Software Flow Control Select
XON1
N/A
XON2
N/A
XOFF1
N/A
XOFF2
N/A
R = Read-Only, W = Write-Only, R/W = Read/Write
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