And the problem with atmel start is that it is broken, from the pwm_basic.dox file in the documentation section of the prject I just setup that only has the PWM output enabled:
/*------------------------------------------------------------------------*/ /**
\addtogroup doc_driver_pwm_basic PWM Basic Drivers
\brief Driver for basic PWM functionality.
The PWM Basic driver provides basic PWM functionality.
The driver has the following features:
- Initializing the hardware implementing the PWM as specified by the user in START
- Supports the number of PWM channels provided by the underlying hardware
- Enable and disable output of PWM channels on I/O pins
- Setting duty cycle for each of the PWM channels
- Load TOP value for the PWM, to specify resolution
- Register ISR callback routine to be called on counter overflow
The application can change the period or duty cycle when the PWM is running.
Functions are provided to configure these two parameters.
Note these are raw register values and the parameter duty_cycle means
the period of first half during one cycle, which should not be larger than
total period value.
The user can hookup a callback to the Overflow ISR, specifying any actions to be
performed by the ISR. To generate code for including a callback handler,
tick the "Include harness for IRQ on overflow"- box in START. START allows the
user to specify the rate R at which to call the ISR callback function. The
callback function is called every R'th ISR execution. If R==0, the callback is
not called by the ISR.
The PWM basic driver uses the same bit width as the Timer or PWM hardware
the driver uses, typically 8 or 16 bits. The data types used in internal
variables and parametyers to functions reflect this bit width.
\section doc_driver_pwm_basic_functional Functional Description
The PWM Basic driver is built on top of a hardware resource providing
PWM functionality. This includes a counter counting from BOTTOM to TOP
(or vice versa), and a compare register per channel. Everytime the value
of the counter matches the value of the compare register, a signal is sent
to an output pin waveform generator, generating an appropriate waveform
on the I/O pin mapped to that PWM channel. The functions
<component_name>_enable_output_chN and <component_name>_disable_output_chN
enables or disables PWM output in the I/O pin mapped
to PWM channel N. When output is enabled, the I/O pin output value is
controlled by the PWM module. When the PWM output is disabled, the I/O pin value
is not controlled by the PWM module, but by other modules or used as
generic I/O pin.
The <component_name>__load_counter() function loads the counter in the Timer
module with the specified value. The <component_name>__load_top() function
loads the TOP value (sometimes called PERIOD) register with the specified
value. For each of the PWM channels 0 to N, a function
<component_name>_load_duty_cycle_chN() loads the duty cycle register of that
PWM channel with the value specified.
The <component_name>_register_callback()-function allows the application to
hookup a callback function to the overflow ISR.
\section doc_driver_pwm_basic_hardware Hardware Dependencies
The PWM Basic driver needs Timer or PWM hardware to be available on the device.
When the user has selected a device and added a PWM component,
the Driver field in the Component Settings pane in START will
let the user select which timer driver to use, select *Drivers:PWM:Basic*
to use the PWM Basic driver.
The Configuration Pane in START will display options that are
dependent on the hardware used to implement the PWM driver.
For example, an option may allow changing the clock prescaling used
to drive the underlying timer hardware.
Different Timer or PWM hardware offer a choice of different PWM modes, such as:
- Single slope
- Dual slope (Phase Correct)
- Dual slope (Phase and Frequency Correct)
The choice of PWM mode is not visible to the PWM Basic driver other than for
initialization of the hardware. The user must make sure that a suitable mode
is chosen when selecting a configuration in START.
In some underlying hardware, the PWM channels are numbered differently from 0 to N.
Frequently, timers with PWM support provides two PWM channels named A and B, where:
- Hardware channel A is mapped to PWM Basic channel 0
- Hardware channel B is mapped to PWM Basic channel 1
In some underlying hardware, some of the PWM modes does not allow the TOP value to be
changed, instead it is fixed at a value such as 0xff, 0x1ff or 0x3ff. For such hardware,
the function <component_name>_load_top() does nothing.
Some underlying hardware have both a buffered and unbuffered version of the Period
and the Compare registers. For these hardwares, the PWM Basic driver writes to
the *buffered* Period and Compare registers in the
<component_name>_load_duty_cycle_ch<n>() and <component_name>_load_period() functions.
\section doc_driver_pwm_basic_software Software Dependencies
The PWM Basic may be configured to use use the interrupt functionality
of the underlying timer or PWM hardware. Make sure that global interrupts
are enabled (using sei()) and that the Interrupt Controller, if
present, is configured so that the Overflow interrupt is serviced
correctly.
\section doc_driver_adc_basic_code Code example
\code
#include <atmel_start.h>
volatile bool isr_executed = false;
volatile adc_result_t measurement;
volatile uint8_t measurement_normalized;
void adc_handler_cb(void){
measurement = ADC_0_get_conversion_result();
measurement_normalized = measurement>>(ADC_0_get_resolution()-8);
isr_executed = true;
}
int main(void)
{
/* Initializes MCU, drivers and middleware */
atmel_start_init();
// Test polled mode
// Get conversion from ADC CH0
measurement = ADC_0_get_conversion(0);
// Get 8 MSB of conversion result
measurement_normalized = measurement>>(ADC_0_get_resolution()-8);
// Test IRQ mode
sei();
ADC_0_register_callback(adc_handler_cb);
// Start conversion from ADC CH0
ADC_0_start_conversion(0);
// Wait for ISR to be execued
while (!isr_executed);
while (1);
}
\endcode
*/
So tell me, am I seeing things or is the PWM documentation mixed up with the ADC documentation? If this is the level of competence they have with the atmel start thing I'd rather spend the time writing my own code rather than trying to fathom out someone elses particularly considering that hey can change that code at any time and i would have to do my research again.
Home
Help
Search
Login
Register
