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With a variety of systems and bridges that move the data between different bus types (i.e. VME to PCI, VXI to PCI, etc.), in order to assist the user in determining how data is ordered, a known floating point value of 0.12345678901234 is loaded at
0x3FBF | is written at address | 0xC00028 |
0x9ADD | is written at address | 0xC0002A |
0x3746 | is written at address | 0xC0002C |
0xF4C6 | is written at address | 0xC0002E |
By reading the value from these addresses, the user can identify the type of DATA(BYTE) swapping that takes place in the system and modify their code accordingly. An example of how to do the swapping is presented in Appendix A.
DETERMINING THE REGISTER ADDRESS
A user wishes to set Channel 2 to the 1.0 V range. Data is to be captured linearly without the use of the low pass filter or timeout control and will trigger from the positive edge of data sent to Channel 2. To accomplish this, the user will access the Control Register for Channel 2 at register offset 0x0058. To determine the register address, this value must be added to the base address and A32 address of the module. In this example, it is assumed that the base address switches are set to 0x19, yielding a base address of 0x19000000. Since the user must write to a register, the function offset is 0x00C00000.
Register Address = Module Base Address + Function Offset + Register Offset
=0x19000000 + 0x00C00000 + 0x00000058
=0x19C00058
By observing the bits in the Control Register, it can be determined what data value should be sent:
0x58 (Channel 2 Offset)
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| Write |
| Reason |
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| 0 |
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| D15 |
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| 0 |
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| D14 |
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| It is recommended that unused register bits | |
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| D13 |
| 0 |
| have 0 written to them |
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| 0 |
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| D12 |
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| 0 |
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| D11 |
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| Disables Timeout Control | |
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| 0 |
| Sets the Channel for Linear Acquisition |
| D10 |
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| 0 |
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| D9 |
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| Sets the Channel for Voltage Mode | |
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| 0 |
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| D8 |
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| 0 |
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| D7 |
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| Sets the Channel for acquisition in the 1.0 V range | |
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| 1 |
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| D6 |
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| 1 |
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| D5 |
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| Disables the 20 kHz Filter on Channel 2 | |
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| 0 |
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| D4 |
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| 0 |
| Sets the channel to trigger on a Positive Slope |
| D3 |
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| 0 |
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| D2 |
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| Selects Channel 2 as the Trigger Source | |
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| 1 |
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| D1 |
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| 0 |
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| D0 |
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SVM2608 Programming | 31 |
