Manual

AT75C310
61
USART User Interface
Base Address USART A: 0xFF018000
Base Address USART B: 0xFF01C000
Notes: 1. This may be 0x18 or 0x418 depending on the value of bootn and modem control inputs.
2. This depends on the value of modem control input signals, as these are reflected in this register.
Offset Register Description Register Name Access Reset State
0x00
Control Register
US_CR Write-only –
0x04
Mode Register
US_MR Read/write 0
0x08
Interrupt Enable Register
US_IER Write-only –
0x0C
Interrupt Disable Register
US_IDR Write-only –
0x10
Interrupt Mask Register
US_IMR Read-only 0
0x14
Channel Status Register
US_CSR Read-only 0x18
(1)
0x18
Receiver Holding Register
US_RHR Read-only 0
0x1C
Transmitter Holding Register
US_THR Write-only –
0x20
Baud Rate Generator Register
US_BRGR Read/write 0
0x24
Receiver Time-out Register
US_RTOR Read/write 0
0x28
Transmitter Time-guard Register
US_TTGR Read/write 0
0x2C
Reserved
––
–
0x30
Receive Pointer Register
US_RPR Read/write 0
0x34
Receive Counter Register
US_RCR Read/write 0
0x38
Transmit Pointer Register
US_TPR Read/write 0
0x3C
Transmit Counter Register
US_TCR Read/write 0
0x40
Modem Control Register
US_MC Write-only –
0x44
Modem Status Register
US_MS Read-only (See Note 2)