From 63419bd270b050b60d20230bbc28dac7f23fe8c9 Mon Sep 17 00:00:00 2001 From: janhauer Date: Wed, 14 Mar 2007 18:14:06 +0000 Subject: [PATCH] Changed default power-down delay to 20ms and added a note to the README as agreed on the telconf. --- .../msp430/adc12/Msp430RefVoltGenerator.h | 2 +- tos/chips/msp430/adc12/README.txt | 34 ++++++++++++------- 2 files changed, 22 insertions(+), 14 deletions(-) diff --git a/tos/chips/msp430/adc12/Msp430RefVoltGenerator.h b/tos/chips/msp430/adc12/Msp430RefVoltGenerator.h index cf7bc197..0050c309 100644 --- a/tos/chips/msp430/adc12/Msp430RefVoltGenerator.h +++ b/tos/chips/msp430/adc12/Msp430RefVoltGenerator.h @@ -42,6 +42,6 @@ // Delay before generator is switched off after it has been stopped (in ms). // This avoids having to wait the 17ms in case the generator is needed again // shortly after it has been stopped (value may be modified). -#define SWITCHOFF_INTERVAL 100 +#define SWITCHOFF_INTERVAL 20 #endif diff --git a/tos/chips/msp430/adc12/README.txt b/tos/chips/msp430/adc12/README.txt index 7acc1c11..98710315 100644 --- a/tos/chips/msp430/adc12/README.txt +++ b/tos/chips/msp430/adc12/README.txt @@ -35,24 +35,32 @@ An application that is written for an MSP430-based platform like 'eyesIFX' or 'telosb' can access the ADC12 in a more efficient way to, for example, do high-frequency sampling through the Msp430Adc12SingleChannel interface. On the MSP430 two additional hardware modules may become relevant when the ADC12 is -used: the internal reference voltage generator and the DMA controller. The -voltage generator outputs stabilized voltage of 1.5 V or 2.5 V, which may be -used as reference voltage in the conversion process. Whether the internal +used: the internal reference voltage generator and the DMA controller. + +The voltage generator outputs stabilized voltage of 1.5 V or 2.5 V, which may +be used as reference voltage in the conversion process. Whether the internal reference voltage generator should be enabled during the conversion is platform-specific (e.g. the light sensor on the 'eyesIFX' requires a stable reference voltage). When an application requires a stable reference voltage during the sampling process it should wire to the Msp430Adc12ClientAutoRVGC component. This assures that when the app is signalled the Resource.granted() event the reference voltage generator outputs a stable voltage (the level is -defined in the configuration data supplied by the application). The DMA -controller can be used to efficiently copy conversion data from ADC data -registers to the application buffer. DMA is only present on MSP430x15x and -MSP430x16x devices. When an application wants to use the DMA it can wire to -the Msp430Adc12ClientAutoDMAC component and then conversion results are -transferred using DMA. Both, enabling the reference generator and using the -DMA, therefore happens transparent to the app. There are four possible -combinations reflected by the following components that an MSP430-based -application may wire to: +defined in the configuration data supplied by the application). There are two +more things to note: first, the generator is not switched off immediately, when +the client calls Resource.release(), but only after some pre-defined interval +(see Msp430RefVoltGenerator.h). This can avoid a power-up delay when multiple +clients are present. Second, one must not forget to wire the AdcConfigure +interface to the Msp430Adc12ClientAutoRVGC or Msp430Adc12ClientAutoDMA_RVGC +component in addition to configuring the ADC through the +Msp430Adc12SingleChannel interface (no nesC warning will be signalled). + +The DMA controller can be used to copy conversion data from the ADC registers +to the application buffer. DMA is only present on MSP430x15x and MSP430x16x +devices. When an application wants to use the DMA it can wire to the +Msp430Adc12ClientAutoDMAC component and then conversion results are transferred +using DMA. Both, enabling the reference generator and using the DMA, therefore +happens transparent to the app. There are four possible combinations reflected +by the following components that an MSP430-based application may wire to: * Msp430Adc12ClientC: no DMA, no automatic reference voltage * Msp430Adc12ClientAutoRVGC: automatic reference voltage, but no DMA @@ -60,7 +68,7 @@ application may wire to: * Msp430Adc12ClientAutoDMA_RVGC: DMA and automatic reference voltage -PINs +I/O PINs -------------------------------------------------------------------- During a conversion the respective ADC port pin (ports 6.0 - 6.7) must be -- 2.39.2