Datasheet

MSP430F261x
MSP430F241x
www.ti.com SLAS541K –JUNE 2007–REVISED NOVEMBER 2012
Peripherals
Peripherals are connected to the CPU through data, address, and control buses and can be handled using all
instructions. For complete module descriptions, see the MSP430x2xx Family User's Guide (SLAU144).
DMA Controller
The DMA controller allows movement of data from one memory address to another without CPU intervention. For
example, the DMA controller can be used to move data from the ADC12 conversion memory to RAM. Using the
DMA controller can increase the throughput of peripheral modules. The DMA controller reduces system power
consumption by allowing the CPU to remain in sleep mode without having to awaken to move data to or from a
peripheral.
Oscillator and System Clock
The clock system in the MSP430F241x and MSP430F261x family of devices is supported by the basic clock
module that includes support for a 32768-Hz watch crystal oscillator, an internal very low-power low-frequency
oscillator, an internal digitally controlled oscillator (DCO), and a high-frequency crystal oscillator. The basic clock
module is designed to meet the requirements of both low system cost and low power consumption. The internal
DCO provides a fast turn-on clock source and stabilizes in less than 1 µs. The basic clock module provides the
following clock signals:
• Auxiliary clock (ACLK), sourced either from a 32768-Hz watch crystal or the internal LF oscillator.
• Main clock (MCLK), the system clock used by the CPU.
• Sub-Main clock (SMCLK), the sub-system clock used by the peripheral modules.
The DCO settings to calibrate the DCO output frequency are stored in the information memory segment A.
Calibration Data Stored in Information Memory Segment A
Calibration data is stored for the DCO and for the ADC12. It is organized in a tag-length-value (TLV) structure.
Table 10. Tags Used by the TLV Structure
NAME ADDRESS VALUE DESCRIPTION
TAG_DCO_30 0x10F6 0x01 DCO frequency calibration at V
CC
= 3 V and T
A
= 25°C at calibration
TAG_ADC12_1 0x10DA 0x08 ADC12_1 calibration tag
TAG_EMPTY - 0xFE Identifier for empty memory areas
Table 11. Labels Used by the ADC Calibration Structure
ADDRESS
LABEL CONDITION AT CALIBRATION SIZE
OFFSET
CAL_ADC_25T85 INCHx = 0x1010, REF2_5 = 1, T
A
= 85°C word 0x000E
CAL_ADC_25T30 INCHx = 0x1010, REF2_5 = 1, T
A
= 30°C word 0x000C
CAL_ADC_25VREF_FACTOR REF2_5 = 1, T
A
= 30°C word 0x000A
CAL_ADC_15T85 INCHx = 0x1010, REF2_5 = 0, T
A
= 85°C word 0x0008
CAL_ADC_15T30 INCHx = 0x1010, REF2_5 = 0, T
A
= 30°C word 0x0006
CAL_ADC_15VREF_FACTOR REF2_5 = 0, T
A
= 30°C word 0x0004
CAL_ADC_OFFSET External V
REF
= 1.5 V, f
ADC12CLK
= 5 MHz word 0x0002
CAL_ADC_GAIN_FACTOR External V
REF
= 1.5 V, f
ADC12CLK
= 5 MHz word 0x0000
CAL_BC1_1MHZ - byte 0x0007
CAL_DCO_1MHZ - byte 0x0006
CAL_BC1_8MHZ - byte 0x0005
CAL_DCO_8MHZ - byte 0x0004
CAL_BC1_12MHZ - byte 0x0003
CAL_DCO_12MHZ - byte 0x0002
CAL_BC1_16MHZ - byte 0x0001
CAL_DCO_16MHZ - byte 0x0000
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