Documentation on ADC12 Components for the MSP430    
 
$Revision: 1.9 $
$Date: 2005/01/21 10:05:51 $
@author Jan Hauer <hauer@tkn.tu-berlin.de>
             
       
There are three ways to access MSP430's ADC12: 

1) Platform independent applications should use
   tos/interfaces/ADCSingle.nc and tos/interfaces/ADCMultiple.nc.
2) Applications written only for the msp430 platform can use
   tos/platform/msp430/MSP430ADC12Single or tos/platform/msp430/MSP430ADC12Multiple.
3) The tos/interfaces/ADC and tos/interfaces/ADCControl
   interfaces are still supported but obsolete, do not use them, because
   they might not be supported in future. 

The use of 1) and 2) is explained TEP101 in beta/teps/, additional
information can be found below. The use of 3) (although obsolete) is also
explained below.
Generell information about the ADC12 can be found in "MSP430 User's Guide" 
Chapter 17. 

1) HIL
Read the section "Hardware Interface Layer (HIL)" in TEP101 in beta/teps/.

2) MSP430ADC12Single and MSP430ADC12Multiple
In a configuration the MSP430ADC12Single and MSP430ADC12Multiple
need to be instantiated with unique("MSP430ADC12").
Read the section "Hardware Adaptation Layer (HAL)" subsection c) in TEP101 
in beta/teps/.
Read the explanation in MSP430ADC12.h for how to use bind().
Look at tinyos-1.x/contrib/eyes/apps/TestADC for an example.

3) ADCC - obsolete -
ADC and ADCControl are used almost the same way as specified in the 
interface definitions, there is only a difference in the meaning of the 
parameters passed to ADCControl.bindPort(). 
"ADCControl.bindPort(uint8_t port, uint8_t adcPort)" needs to be called once for
each port that is to be sampled through the ADCC. This binds the interface
instance number (="port") to the actual input-channel and some other settings
coded in "adcPort". The reason for this is that any subsequent calls to
"ADC.getData()" will only require the port-number to identify the corresponding
settings. The port-number is not passed as a parameter of "ADC.getData()", but
it is the number of the ADC-interface instance (ADC is a parameterized
interface). That's why it is necessary to always have the "port"-parameter in
"ADCControl.bindPort(uint8_t port, uint8_t adcPort)" be the same as the
interface parameter of the ADC interface through which your component is wired
to ADCC. Actually this is how the interface ADCControl was intended anyway.

a) The "port" Parameter of ADCControl.bindPort 

Since the "port" parameters reflect the interface instance they must all be
different starting from 0 (to keep RAM usage to minimum as the interface IDs are
used to index and allocate an array).  This is achieved by having a separate
header file for each sensor component and having a unique constant created for
each sensor with unique("ADCPort"), see below for an example.

b) The "adcPort" Parameter of ADCControl.bindPort 

The parameter "adcPort" encodes the input channel and the reference voltage. If
reference voltage VREF+ is used it additionally holds information about the
required value of VREF+ (1.5V or 2.5V). In detail:

 bit 0-3: input channel
 bit 4-6: reference voltage
 bit 7: voltage level (ignored if reference voltage != VREF+)

There is a macro ASSOCIATE_ADC_CHANNEL in MSP430ADC12.h that can be used to
encode this information. In the header file for a sensor component there should
be a constant that reflects the actual settings for this sensor. An example for
the "port" and "adcPort" parameters (see InternalVoltage.h):

enum
{
  // the "port" parameter and interface id
  TOS_ADC_INTERNAL_VOLTAGE_PORT = unique("ADCPort"),

  // the actual settings, "adcPort" parameter
  TOSH_ACTUAL_ADC_INTERNAL_VOLTAGE_PORT = ASSOCIATE_ADC_CHANNEL( 
           INTERNAL_VOLTAGE, 
           REFERENCE_VREFplus_AVss, 
           REFVOLT_LEVEL_1_5), 
};


WIRING EXAMPLE:

first wire ADCC to your configuration:

    MyApp.ADC -> ADCC.ADC[TOS_ADC_INTERNAL_VOLTAGE_PORT];
    MyApp.ADCControl -> ADCC.ADCControl;

then bind and do the conversion in you module.

    call ADCControl.init();
    call ADCControl.bindPort(TOS_ADC_INTERNAL_VOLTAGE_PORT, 
                                   TOSH_ACTUAL_ADC_INTERNAL_VOLTAGE_PORT);
    call ADC.getData();