AEROFLEX GAISLER
75
RT-SPW-ROUTER
Copyright Aeroflex Gaisler AB
June 2012, Version 1.2
7
Serial Debug Interface
7.1
Overview
The interface consists of a UART connected to the AMBA AHB bus as a master. A simple communi-
cation protocol is supported to transmit access parameters and data. Through the communication link,
a read or write transfer can be generated to any address on the AMBA AHB bus.
7.2
Operation
7.2.1
Transmission protocol
The interface supports a simple protocol where commands consist of a control byte, followed by a 32-
bit address, followed by optional write data. Write access does not return any response, while a read
access only returns the read data. Data is sent on 8-bit basis as shown below.
Figure 22. Block diagram
RX
TX
Receiver shift register
Transmitter shift register
AHB master interface
AHB data/response
AMBA AHB
Serial port
Controller
8*bitclk
Baud-rate
generator
AMBA APB
Figure 23. Data frame
Start D0
Stop
D6
D5
D4
D3
D2
D1
D7
Figure 24. Commands
Write Command
11 Length -1
Addr[31:24]
Addr[7:0]
Addr[15:8]
Addr[23:16]
Data[31:24]
Data[7:0]
Data[15:8]
Data[23:16]
Send
10 Length -1
Addr[31:24]
Addr[7:0]
Addr[15:8]
Addr[23:16]
Send
Read command
Receive
Data[31:24]
Data[7:0]
Data[15:8]
Data[23:16]
