VMEbus
Hardware Essentials
The Board Address and Slave Address Modifier to which the RF3570 responds on the VMEbus are set with jumpers on the board.
The RF3570 adapter is an A16 SLAVE device on the VMEbus. In keeping with VMEbus Specifications, the Address Modifier for selection of this type of device can be either 29H or 2DH. Since there is only one bit
difference between the two values, a single jumper is provided to select an Address Modifier.
AM5 AM4 AM3 AM1 AMO
1
o
1o
1VMEbus Address Modifier Lines
Figure 2-2: Choosing an Address Modifier
Choose Address Modifier 2DH by removing the jumper, when you wish to reserve the RF3570 registers for short supervisory access. Choose 29H by inserting the jumper, if you wish to allow short non-privileged access:
Board Addressing
Choosing an Address Modifier
Hex Address Modifier
Function
Code 5 4 3 2 1 0
20 1 0 1 1 0 1 Short Supervisory Access 29 1 0 1 0 0 1 Short Non-Privileged Access
Table 2-1: VMEbus Address Modifiers for RF3560 The factory setting for the RF3570 Slave Address Modifier
is 2DH; the jumper is out.
The location and setting of this jumper is described in Chapter 3.
Rimfire 3570 User's Guide 2-5
Choosing a VMEbus Address
Hardware Ports:
General
Hardware Port Addresses
With the address jumpers on the RF3570 board, you set the upper 7 bits of the Board Address. This effectively reserves 512 bytes of VMEbus 16- bit address space.
Within the reserved area, the RF3570 adapter has fOUI
register ports that are the foundation of its communication scheme.
A 7 A6 AS A2 A 1 AO
Figure 2-3: Address Line Decoding
The factory setting for the RF3570 VMEbus Address is to jumper A12 making the default base address EEOOH.
Details about the location and setting of the jumpers can be found in Chapter 3, Hardware Installation.
There are four ports that are used to communicate with the RF3570 adapter: Address Buffer Port; Channel Attention Port; Status Port; and Reset Port. The address and function of each port is described in this section.
Each of the Hardware ports can be addressed as an offset from the base address, set with jumpers on the board.
Further, all ports can be accessed in 16-bit mode. To address a specific port you must add the correct offset to the base address value. The offset values for the RF3570 hardware ports are described in Figure 2- 4.
Address Buffer OOH Write
Hardware Essentials
Example Port Addresses
Using the factory set Base Address for the RF3570, EEOOH, the Hardware Port Addresses would be:
Address Port
=
EEOOHChannel Attention Port = EE08H Status Port = EE10H
Reset Port = EE18H
Figure 2-4 also indicates how each port can be accessed by the Host: read or write.
An overview of the operation of all of the Hardware Ports is provided next. The overview is followed by a detailed description of each Hardware Port that focuses on the rules of operation.
Address Buffer Port
This port is instrumental in setting up the RF3570 adapter I/O operation. With it you can do two things:
1.) Set system bus transfer characteristics such as bus width and byte/word swapping for subsequent operations.
Usually this is done only with the first command sent to the board, when you are initializing the board for opera-tion in your system.
2.) Pass the address of a Single Command Structure to the adapter. Any time you wish to issue a Single Command, you must use the Address Buffer Port to pass the address structure. Most often, the first Single Command executed contains a command to Start Command List. This function of the port is only used when issuing a Single Command.
Channel Attention Port
The Channel Attention Port is your means of informing the RF3570 adapter that a command is ready to be
executed. The value you write to this port tells the adapter what kind of Command Structure to expect. Before you write to the Channel Attention Port you must set-up the appropriate Command Structure in the system memory space you will be directing the adapter to read.
Overview of the Ports
Rimfire 3570 User's Guide 2-7
Address Buffer Port
Status Port
This port is used to read status from the adapter. There are two types of status that can be read: General Status -returned after a command completes during normal operation; and Reset Status - returned during board self-test at reset or power-up.
Reset Port
With the Reset Port you are able to initiate, through software, a reset identical to a hardware reset.
The Address Buffer Port is a write-only port. It is used when you wish to execute a command using a Single Command Structure. It is loaded with: the starting system address of the structure; an address modifier value to be used when reading the Parameter Block contained in the structure; and a byte of control information through which you may instruct the RF3570 adapter about subsequent operation.
The Address Buffer Port register is three words deep and 16 bits wide. To pass all three words requires three writes to the port:
• The first write must contain the Control byte and Address Modifier.
• The second write contains the Most Significant Word (MSW) of the Single Command Structure address in system memory.
• The last write contains the Least Significant Word (LSW) of the Single Command Struclure address.
The order of these writes is illustrated in Figure 2-5:
Hardware Essentials
A description of each of the fields of the Address Buffer Port follows.
Address Modifier Field The Address Modifier (AM) Field of the Address Buffer Port is used to specify the Address Modifier value that the RF3570 adapter should use when reading the first
Parameter Block.
Control Field Use this byte-wide field to tailor the RF3570 adapter's use of the system bus. With it, you can set-up the adapter to:
• transfer data in 16-bit or 32-bit mode on the VMEbus.
• byte or word swap command structures to be compatible with the Dy'te and word ordering of either Inter or Motorola arcfiitectures.
• b~e ~r word swap data to change the data byte ordenng.
Byte and word swapping are further discussed in Chapter 7, Details of Usage.
The bit meanings of the Control Field are as follows:
Figure 2-6: Control Field of Address Buffer Port For any of the control bits to be considered valid by the adapter,
the SET bit must be one.
esc Byte Swapping Control:
Defines whether high and low bytes of a word will be swapped during transfer of status and parameter blocks.
o
~ No swapping.1 ~ Change byte order.
NOTE:
Rimfire 3570 User's Guide 2-9