c8051f410 Silicon Laboratories, c8051f410 Datasheet - Page 123

• Manufacturer Part Number: c8051f410
• Description: 2.0 V, 32/16 Kb Flash, Smartclock, 12-bit Adc
• Manufacturer: Silicon Laboratories

14.2. Preparing for a CRC Calculation
To prepare CRC0 for a CRC calculation, software should select the desired polynomial and set the initial
value of the result. Two polynomials are available: 0x1021 (16-bit) and 0x04C11DB7 (32-bit). The CRC0
result may be initialized to one of two values: 0x00000000 or 0xFFFFFFFF. The following steps can be
used to initialize CRC0.
14.3. Performing a CRC Calculation
Once CRC0 is initialized, the input data stream is sequentially written to CRC0IN, one byte at a time. The
CRC0 result is automatically updated after each byte is written.
14.4. Accessing the CRC0 Result
The internal CRC0 result is 32-bits (CRC0SEL = 0b) or 16-bits (CRC0SEL = 1b). The CRC0PNT bits
select the byte that is targeted by read and write operations on CRC0DAT and increment after each read or
write. The calculation result will remain in the internal CR0 result register until it is set, overwritten, or addi-
tional data is written to CRC0IN.
14.5. CRC0 Bit Reverse Feature
CRC0 includes hardware to reverse the bit order of each bit in a byte as shown in Figure 14.2. Each byte
of data written to CRC0FLIP is read back bit reversed. For example, if 0xC0 is written to CRC0FLIP, the
data read back is 0x03. Bit reversal is a useful mathematical function used in algorithms such as the FFT.
Step 1. Select a polynomial (Set CRC0SEL to ‘0’ for 32-bit or ‘1’ for 16-bit).
Step 2. Select the initial result value (Set CRC0VAL to ‘0’ for 0x00000000 or ‘1’ for 0xFFFFFFFF).
Step 3. Set the result to its initial value (Write ‘1’ to CRC0INIT).
Figure 14.2. Bit Reverse Register
CRC0FLIP
CRC0FLIP
Read
Write
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