Assigning VME addresses

Change Log
April 29,2004	Initial version Ron Fox fox@nscl.msu.edu

This application note describes considerations you should take into account when assigning VME addresses to modules in the NSCL data acquisition system.

• First we will give a short background section that describes the VME bus.
• We will then describe the base addresses and address modifiers of standard modules.
• We will describe how Geographically addressed modules appear on the VME bus at the NSCL
• We will provide an annotated map of the VME address space.
• Finally we will give a sample configuration and associated address map.

Background

This section gives a simplified description of how addressing on the VME bus works. The VME bus actually supports a much richer set of addressing models than those described here, however the description in this section suffices for the bulk of the VME configurations you will need to deal with at the NSCL.

The VME bus should be thought of as three large chunks of memory. Which of the three chunks of memory is selected at any given time is determined by the bus operation's address modifier or AM. Each chunk of memory (selected by an address modifier) is called an address space. Within each chunk of memory, each byte has a unique address.

The names, shorthand names and characteristics of each address space are shown in the table below:

Space name	Shorthand	Characteristics
Short IO	A16	16 bits of address provide up to 65K bytes of address space intended to be used by I/O modules. Each module lives on a 256 byte boundary
Standard	A24	24 bits of address allow up to 16Mbytes of address space.
Extended	A32	32 bits of address allow up to 4Gbytes of address space.

Note again, that a location, say 0x1234 in A16 space is different from the same location 0x1234 in A24 space which in turn selects a different location in A32 space. The address spaces are all distinct and don't overlap unless a specific module chooses to accept addresses with multiple address modifiers.

Standard modules and locations

There are several modules that may appear in your system that have a very standard set of addresses:

• The CAEN V262 used to trigger your system. Setting the base address of this module to something other than the recommended value will mean that the module is not capable of being used as a trigger module.
• The CES CBD 8210 CAMAC interface. If you are using a mixed VME/CAMAC system it is important to note that this module
• The Wiener CAMAC interface.

The V262 is in A24 space at base address 0x444400 and requires 256 bytes of address space.

The CES CBD 8210 CAMAC interface is in A24 space, with a base address that depends on the branch number set in its front panel thumbwheels:

Branch	Address range.
0	0x800000 - 0x87ffff
1	0x880000 - 0x8fffff
2	0x900000 - 0x97ffff
3	0x980000 - 0x9fffff
4	0xa00000 - 0x97ffff
5	0xa80000 - 0xafffff
6	0xb00000 - 0xb7ffff
7	0xb80000 - 0xbfffff

The Wiener CAMAC interface may not be used in conjunction with the CES CBD 8210 interface and, due to the fact that the 8210 is an "end of life" module it is suggested that all new systems using CAMAC use this interface instead. While the Wiener CAMAC interface has a quite flexible set of base addresses (all in the A24 space), in order to retain source compatibility with the camac support macros developed for the CBD8210, we limit the set of base addresses you should use for this module. The switch settings for this module are described completely in its application note at: http://docs.nscl.msu.edu/daq/appnotes/WienerNotes.txt

The table below summarizes the set of addresses in A24 space taken up by this module (we support up to 8 crates in a VME bus).

Crate	Address range
0	0x800000 - 0x807fff
1	0x808000 - 0x80ffff
2	0x810000 - 0x817fff
3	0x818000 - 0x81ffff
4	0x820000 - 0x827fff
5	0x828000 - 0x82ffff
6	0x830000 - 0x837fff
7	0x838000 - 0x83ffff

Geographically addressed modules

Physicists used to working with CAMAC may have difficulty remembering to set address switches or jumpers. This is especially true when replacing a suspect module deep into the midnight shift. The geographical addressing that CAMAC supports is a much simpler scheme.

CERN has defined several extensions to the VME bus that are carried on a third (middle) connector on the backplane. One of these extensions encodes the slot number on a set of pins in this middle connector. Modules can use this encoding to set their base addresssing.

Note that since that time, the VME standards committee has defined a newer VME standard called VME64 that supports 64 bit addressing. An extension to that standard called VME64x also supports geographical addressing, in a different way.

At this time, all of the backplanes in use in NSCL experimental setups support the CERN style geographical addressing extensions. Where modules provide support for it, we encourage the use of geographical addressing as this will simplify your setup. At this time the following families of modules we have in the pool that support CERN style geographical addressing extensions:

• CAEN 32 channel digitizers (V775, V785, V792, V862)
• CAEN V775 multihit TDC
• CAEN V1190/1290 multihit TDC (coming soon).
• Jtec XLM

Due to hardware differences, two schemes are used to handle these modules.

CAEN Modules

The CAEN modules only support a subset of functionality needed to set them up when geographically addressed. One of the setup operations possible, however is to program an A32 base address for the module. Once accessed via this programmed A32 base address, the module can be fully used. Therefore, when using the CAEN modules it is important to recognize that they will occupy two regions of address space: an A24 space determined by the module's slot, and an A32 space determined by the software that sets up the module.

These address ranges are shown in the table below:

Slot	Geographical range	A32 address range
2 (*)	0x100000-0x108fff	0x02000000 - 0x02008fff
3	0x180000-0x188fff	0x03000000 - 0x03008fff

+----------+------------- -------+------------------------------+

n	n<<19 - n<<19+0x8fff	n << 24 - n << 24 + 0x8fff
20	0xa00000-0xa08fff	0x14000000 - 0x14008fff

(*) - Slot 1 of a VME bus must always be occupied by a system controller module. At the NSCL, this role is fulfilled by the SBS/Bit3 PCI/VME bus adapter.

Jtec XLM

Slot	Address range (always geographical)
2(*)	0x10000000 - 0x10ffffff
3	0x18000000 - 0x18ffffff
4	0x20000000 - 0x20ffffff
...	...
n	n << 27 - n << 27 + 0xffffff
20	0xa0000000 - 0xa0ffffff

(*) - Slot1 of a VME bus must always be occupied by a system controller module. At the NSCL, this role is fulfilled by the SBS/Bit3 PCI/VME bus adapter.

Annotated Map of the VME bus

The purpose of this section is to provide an annotated map of the VME bus showing the 'danger zones'. When laying out a VME bus address map for your application you have two choices:

• Assign modules only to address ranges that are not in the danger zones shown in the tables in this section. In that case you can use the tables in this section as a starting point for building your own documented address map (a worksheet so to speak).
• Assign module address ranges that overlap ranges you know you won't use, for example, if your setup will include a module in slot 15 that requires a base address, you could choose the A24 or A32 address ranges of the CAEN geographically addressed modules for slot 15, or the XLM slot 15 address range since these modules are gaurenteed not to be installed as long as your module is in slot 15.

A16 Address map:

Range	Usage
0x0000 - 0xffff	Uncommitted

A24 address map:

In the table below note that:

• There are potential conflicts between CAEN 32 channel digitizers in Slot 16 - 20 and the CES Camac interface. In addtion if using the Wiener CAMAC interface, crate 0,1 will conflict with slot 16.
• There are potential conflicts between the Wiener CAMAC interface and the CES branch 0 CAMAC interface.
• There is are reasonably large uncomitted chunks of address space from 0x000000 through 0x0fffff (1Mbytes) ( and 0xc00000 through 0xffffff (4Mbytes).

Range	Usage
0x000000 - 0x0fffff	Uncommitted
0x100000 - 0x108fff	CAEN Geo slot 2
0x109000 - 0x17ffff	Uncommitted
0x180000 - 0x188fff	CAEN Geo slot 3
0x189fff - 0x1fffff	Uncomitted
0x200000 - 0x208fff	CAEN Geo slot 4
0x209000 - 0x27ffff	Uncommitted
0x280000 - 0x288fff	CAEN Geo slot 5
0x289fff - 0x2fffff	Uncommitted
0x300000 - 0x308fff	CAEN Geo slot 6
0x309000 - 0x37ffff	Uncommitted
0x380000 - 0x388fff	CAEN Geo slot 7
0x389fff - 0x3fffff	Uncommitted
0x400000 - 0x408fff	CAEN Geo slot 8
0x409fff - 0x443fff	Uncommitted [a bit more really]
0x444400 - 0x4444ff	CAEN V262 IO (trigger)
0x444500 - 0x47ffff	Uncommitted
0x480000 - 0x488fff	CAEN Geo slot 9
0x489000 - 0x4fffff	Uncommitted.
0x500000 - 0x508fff	CAEN Geo slot 10
0x509000 - 0x57ffff	Uncommitted.
0x580000 - 0x588fff	CAEN Geo slot 11
0x589000 - 0x5fffff	Uncommitted
0x600000 - 0x608fff	CAEN Geo Slot 12
0x609000 - 0x67ffff	Uncommitted
0x680000 - 0x688fff	CAEN Geo Slot 13
0x689000 - 0x6fffff	Uncommitted
0x700000 - 0x708fff	CAEN Geo slot 14
0x709000 - 0x77ffff	Uncomittted
0x780000 - 0x788fff	CAEN Geo slot 15
0x800000 - 0x808fff	CAEN Geo slot 16 OR CES Branch 0 OR Wiener Crate 0 (to 0x807fff) and Wiener Crate 1 (from 0x808000)
0x809000 - 0x808fff	Wiener Crate 1 (from 0x808000) OR CES Branch 0
0x810000 - 0x817fff	Wiener Crate 2 OR CES Branch 0
0x818000 - 0x81ffff	Wiener Crate 3 OR CES Branch 0
0x820000 - 0x827fff	Wiener crate 4 OR CES Branch 0
0x828000 - 0x82ffff	Wiener Crate 5 OR CES Branch 0
0x830000 - 0x837fff	Wiener crate 6 OR CES Branch 0
0x838000 - 0x83ffff	Wiener crate 7 OR CES Branch 0
0x840000 - 0x87ffff	CES Branch 0
0x880000 - 0x888fff	CAEN Geo slot 17 OR CES Branch 1
0x889000 - 0x8fffff	CES Branch 1
0x900000 - 0x908fff	CAEN Geo slot 18 OR CES Branch 2
0x909000 - 0x97ffff	CES Branch 2

| | CES Branch 3

0x989000 - 0x9fffff	CES Branch 3
0xa00000 - 0xa08fff	CAEN Geo slot 20 OR CES Branch 4
0xa09000 - 0xa7ffff	CES Branch 4
0xa80000 - 0xafffff	CES Branch 5
0xb00000 - 0xb7ffff	CES Branch 6
0xb80000 - 0xbfffff	CES Branch 7
0xc00000 - 0xffffff	Uncommitted

A32 Address map

Some observations:

• There are large-ish unused address segments from 0x00000000 through 0x01ffffff (16Mbytes) and from 0xa0000000 through 0xffffffff (1GByte).
• A JTEC XLM in slot 2 will conflict with CAEN modules in slots 17 through 20. It is probably best, therefore to stuff CAEN modules from the low numbered slots and JTEC XLM"s from the high numbered slots.

0x00000000 - 0x01ffffff	Uncommitted
0x02000000 - 0x02008fff	CAEN slot 2 programmed A32 space
0x02009000 - 0x02ffffff	Uncommitted
0x03000000 - 0x03008fff	CAEN Slot 3 programmed A32 space
0x03009000 - 0x03ffffff	Uncommitted.
0x04000000 - 0x04008fff	CAEN Slot 4 programmed A32 space
0x04009000 - 0x04ffffff	Uncommitted
0x05000000 - 0x05008fff	CAEN Slot 5 programmed A32 space
0x05009000 - 0x05ffffff	Uncommitted .
0x06000000 - 0x06008fff	CAEN Slot 6 programmed A32 space
0x0600900 - 0x06ffffff	Uncommitted .
0x0700000 - 0x07008fff	CAEN Slot 7 programmed A32 space
0x07009000 - 0x07ffffff	Uncommitted
0x08000000 - 0x08008fff	CAEN slot 8 programmed A32 space
0x08009000 - 0x08ffffff	Uncommitted .
0x09000000 - 0x09008fff	CAEN Slot 9 programmed A32 space
0x09009000 - 0x09ffffff	Uncommitted
0x0a000000 - 0x0a008fff	CAEN Slot 10 programmed A32 space
0x0a009000 - 0x0affffff	Uncommitted
0x0b000000 - 0x0b08ffff	CAEN Slot 11 programmed A32 space
0x0b009000 - 0x0bffffff	Uncommitted
0x0c000000 - 0x0c008fff	CAEN Slot 12 programmed A32 space
0x0c009000 - 0x0cffffff	Uncommitted
0x0d000000 - 0x0d008fff	CAEN slot 13 programmed a32 space
0x0d009000 - 0x0dffffff	Uncommitted .
0x0e000000 - 0x0e008fff	CAEN Slot 14 programmed A32 space
0x0e009000 - 0x0effffff	Uncommitted
0x0f000000 - 0x0f008fff	CAEN Slot 15 programmed A32 space
0x0f009000 - 0x0fffffff	Uncommitted
0x10000000 - 0x10008fff	CAEN Slot 16 programmed A32 space OR JTEC XLM slot 2
0x10009000 - 0x10ffffff	JTEC XLM Slot 2
0x11000000 - 0x11008fff	CAEN Slot 17 programmed A32 space OR JTEC XLM Slot 2
0x11009000 - 0x11ffffff	JTEC XLM Slot 2
0x12000000 - 0x12008fff	CAEN Slot 18 programmed A32 space OR JTEC XLM Slot 2
0x12009000 - 0x12ffffff	JTEC XLM Slot 2
0x13000000 - 0x13008fff	CAEN Slot 19 programmed A32 space OR JTEC XLM Slot 2
0x13009000 - 0x13ffffff	JTEC XLM Slot 2
0x14000000 - 0x14008fff	CAEN Slot 20 programmed A32 space OR
0x14009fff - 0x17ffffff	JTEC XLM Slot 2
0x18000000 - 0x1fffffff	JTEC XLM Slot 3
0x20000000 - 0x27ffffff	JTEC XLM Slot 4
0x28000000 - 0x2fffffff	JTEC XLM Slot 5
0x30000000 - 0x37ffffff	JTEC XLM Slot 6
0x38000000 - 0x3fffffff	JTEC XLM slot 7
0x40000000 - 0x47ffffff	JTEC XLM Slot 8
0x48000000 - 0x4fffffff	JTEC XLM Slot 9
0x50000000 - 0x57ffffff	JTEC XLM Slot 10
0x58000000 - 0x5fffffff	JTEC XLM Slot 11
0x60000000 - 0x67ffffff	JTEC XLM Slot 12
0x68000000 - 0x6fffffff	JTEC XLM Slot 13
0x70000000 - 0x77ffffff	JTEC XLM Slot 14
0x78000000 - 0x7fffffff	JTEC XLM Slot 15
0x80000000 - 0x87ffffff	JTEC XLM Slot 16
0x88000000 - 0x8fffffff	JTEC XLM Slot 17
0x90000000 - 0x97ffffff	JTEC XLM Slot 18
0x98000000 - 0x9fffffff	JTEC XLM Slot 19
0xa0000000 - 0xa7ffffff	JTEC XLM Slot 20
0xa8000000 - 0xffffffff	Uncommitted.

Sample Configuration

In this section we layout a sample configuration, and document the resulting address map. Suppose we have an experiment that will require 64 channels of ADC (2 x CAEN V785), 64 channels of TDC (2 x CAEN V775), and 32 channels of QDC (1 x CAEN V892. We will have a programmable trigger that is managed by a pair of JTEC XLM modules as well as a CAEN V 262 IO module to accept the final trigger decision. We will have 32 channels of scaler that are readout via an SIS 3820 scaler. In order to avoid the potential address conflicts between The CAEN digitizers and the JTEC XLM, we'll put the XLM modules in slot2 19 and 20. We'll start inserting the CAEN digitizers at the left of the crate:

CAEN V785's in slots 2,3 CAEN V775's in slots 4,5 CAEN V892 in slot 6

The SIS 3820 is an A32 only module that requires a 16Mbyte chunk of address space. The switches allow us to set the top two hexadecimal digits of the module's base address. While the module supports Geographical addressing, it uses the VME 64x method which is not compatible with the NSCL backplanes. We will locate the SIS3820 at the bottom of the large uncomitted address space past the 'last' XLM (base address 0xa8000000 (switches set: J1 EN_A32 in , EN_GEO out, Rotary switches: SW4 Set to A and SW 3 set to 8). This module can be inserted in any unused slot. We'll choose slot 10.

This gives us the following address maps

A24 address map:

A24 space has:

• The geographical addresses for the CAEN V775,785, 892.
• The address space required by the CAEN V262

Range:	Contents
0x000000 - 0x0fffff	Unused
0x100000 - 0x108fff	CAEN V785 in slot 2
0x209000 - 0x17ffff	Unused
0x180000 - 0x18ffff	CAEN V785 in slot 3
0x189fff - 0x1fffff	Unused
0x200000 - 0x208fff	CAEN V775 in slot 4
0x209000 - 0x27ffff	Unused
0x280000 - 0x288fff	CAEN V775 in slot 5
0x289000 - 0x2fffff	Unused
0x300000 - 0x308fff	CAEN V792 in slot 6
0x309000 - 0x443fff	Unused
0x444400 - 0x4444ff	CAEN V262 IO register
0x444500 - 0xffffff	Unused.

A32 address Map

This address space has:

• The CAEN digitizer module's relocated addresses corresponding to slots 2 through 6.
• 2 JTEC XLMS (slots 19, 20)
• 1 SIS 3820 scaler module.

This gives the following address map:

Adress range	Contents
0x00000000 - 0x01ffffff	Uncommitted
0x02000000 - 0x02008fff	CAEN slot 2 programmed A32 space
0x02009000 - 0x02ffffff	Uncommitted
0x03000000 - 0x03008fff	CAEN Slot 3 programmed A32 space
0x03009000 - 0x03ffffff	Uncommitted.
0x04000000 - 0x04008fff	CAEN Slot 4 programmed A32 space
0x04009000 - 0x04ffffff	Uncommitted
0x05000000 - 0x05008fff	CAEN Slot 5 programmed A32 space
0x05009000 - 0x05ffffff	Uncommitted .
0x06000000 - 0x06008fff	CAEN Slot 6 programmed A32 space
0x06009fff - 0x97ffffff	Uncommitted
0x98000000 - 0x9fffffff	JTEC XLM in slot 19
0xa0000000 - 0xa7ffffff	JTEC XLM in slot 20
0xa8000000 - 0xa81fffff	SIS 3820 scaler (slot 10)