LPC1837FET256,551 NXP Semiconductors, LPC1837FET256,551 Datasheet - Page 984

• Manufacturer Part Number: LPC1837FET256,551
• Description: Microcontrollers (MCU) 32BIT ARM CORTEX-M3 MCU 136KB SRAM
• Manufacturer: NXP Semiconductors
• Series: LPC18xxr

Specifications of LPC1837FET256,551

• Core: ARM Cortex M3
• Core Processor: ARM® Cortex-M3™
• Core Size: 32-Bit
• Speed: 150MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, Microwire, SD/MMC, SPI, SSI, SSP, UART/USART, USB OTG
• Peripherals: Brown-out Detect/Reset, DMA, I²S, Motor Control PWM, POR, PWM, WDT
• Number Of I /o: 80
• Program Memory Size: 1MB (1M x 8)
• Program Memory Type: FLASH
• Eeprom Size: -
• Ram Size: 136K x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 3.6 V
• Data Converters: A/D 16x10b; D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 256-LBGA
• Lead Free Status / Rohs Status: Details
• Other names: 935293795551

NXP Semiconductors
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User manual
towards 0. When either counter reaches its terminal value both counters are disabled and
the MEAS bit is reset to 0. The current values of the counters can then be read out and
the selected frequency obtained by the following equation:
If RCNT is programmed to a value equal to the core clock frequency in kHz and reaches 0
before the FCNT counter saturates, the value stored in FCNT would then show the
measured clock’s frequency in kHz without the need for any further calculation.
Note that the accuracy of this measurement can be affected by several factors:
Table 931. FREQ_MON register (FREQ_MON, address 0x4005 0014) bit description
Bit
8:0
22:9
23
1. Quantization error is noticeable if the ratio between the two clocks is large (e.g.
2. Due to synchronization, the counters are not started and stopped at exactly the same
3. The measured frequency can only be to the same level of precision as the reference
100 kHz vs. 1 kHz), because one counter saturates while the other still has only a
small count value.
time.
frequency.
Symbol
RCNT
FCNT
MEAS
All information provided in this document is subject to legal disclaimers.
fselected
Value
0
1
Rev. 00.13 — 20 July 2011
=
Description
9-bit reference clock-counter value
14-bit selected clock-counter value
Measure frequency
RCNT and FCNT disabled
Frequency counters started
------------------------------------------------------------------------- -

Qref initial

Qselected
 Qref final
–




fref
Chapter 42: Appendix
UM10430
Reset
value
0
0
0
© NXP B.V. 2011. All rights reserved.
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