LPC540xx
NXP Semiconductors
32-bit ARM Cortex-M4 microcontroller
7.18 CRC engine
The Cyclic Redundancy Check (CRC) generator with programmable polynomial settings
supports several CRC standards commonly used. To save system power and bus
bandwidth, the CRC engine supports DMA transfers.
7.18.1 Features
• Supports three common polynomials CRC-CCITT, CRC-16, and CRC-32.
– CRC-CCITT: x16 + x12 + x5 + 1
– CRC-16: x16 + x15 + x2 + 1
– CRC-32: x32 + x26 + x23 + x22 + x16 + x12 + x11 + x10 + x8 + x7 + x5 + x4 + x2 + x + 1
• Bit order reverse and 1’s complement programmable setting for input data and CRC
sum.
• Programmable seed number setting.
• Supports CPU PIO or DMA back-to-back transfer.
• Accept any size of data width per write: 8, 16 or 32-bit.
– 8-bit write: 1-cycle operation.
– 16-bit write: 2-cycle operation (8-bit x 2-cycle).
– 32-bit write: 4-cycle operation (8-bit x 4-cycle).
7.19 Temperature sensor
The temperature sensor transducer uses an intrinsic pn-junction diode reference and
outputs a CTAT voltage (Complement To Absolute Temperature). The output voltage
varies inversely with device temperature with an absolute accuracy of better than ±5 C
over the full temperature range (40 C to +105 C). The temperature sensor is only
approximately linear with a slight curvature. The output voltage is measured over different
ranges of temperatures and fit with linear-least-square lines.
After power-up, the temperature sensor output must be allowed to settle to its stable value
before it can be used as an accurate ADC input.
For an accurate measurement of the temperature sensor by the ADC, the ADC must be
configured in single-channel burst mode. The last value of a nine-conversion (or more)
burst provides an accurate result.
7.20 Security features
• OTP memories for AES key storage and customer use.
• Random number generator (RNG).
• Unique ID for each device.
7.20.1 SHA-1 and SHA-2
The Hash peripheral is used to perform SHA-1 and SHA-2 (256) based hashing. A hash
takes an arbitrarily large message or image and forms a relatively small fixed size
“unique” number called a digest. The data is fed by words from the processor, DMA, or
hosted access; the words are converted from little-endian (ARM standard) to big-endian
(SHA standard) by the block.
LPC540xx
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© NXP Semiconductors N.V. 2018. All rights reserved.
Product data sheet
Rev. 1.8 — 22 June 2018
82 of 168
NXP [ NXP ]
