Peripheral Simulation

For Atmel AT91SAM7X128 — Analog/Digital Converter

Simulation support for this peripheral or feature is comprised of:

• Dialog boxes which display and allow you to change peripheral configuration.
• VTREGs (Virtual Target Registers) which support I/O with the peripheral.

These simulation capabilities are described below.

Analog/Digital Converter Dialog

The Analog/Digital Converter dialog displays and configures the A/D converter. The controls in this dialog are separated into several logical groups.

Control

• ADC_CR (ADC Control Register) displays and configures the A/D Converter control register.
• SWRST (Software Reset) button resets the ADC simulating a hardware reset.
• START (Start Conversion) button begins analog-to-digital conversion.

External Trigger

• ADTRG (ADC External Trigger Pin) displays the level of the ADC External Trigger input.

Mode

• ADC_MR (ADC Mode Register) displays and configures the A/D Converter mode of operation.
• TRGSEL (Trigger Selection) selects the hardware trigger source.
• TRGEN (Trigger Enable) enables the hardware trigger defined by the trigger selection (TRGSEL), if set. If reset, ADC conversions can only be triggered by software.
• LOWRES (Resolution) produces 8-bit digital output in the convert registers, if set. The convert registers produce 10-bit output, if reset.
• SLEEP (Sleep Mode) deactivates the ADC to save power when it is not being used.
• STARTUP (Startup Time) contains the minimum time (in clock cycles) needed to guarantee the best converted value after the ADC has been started.
• SHTIM (Sample and Hold Time) contains the minimum time (in clock cycles) needed to guarantee the best converted value between to ADC channel selections.
• PRESCAL (Prescaler Rate Selection) defines how the master clock is converted into the ADC clock.
• Rate[Hz] is the converted ADC clock value.

Channel Status

• ADC_CHSR (Channel Status Register) enables or disables conversion channels 0-7.
• CH7-CH0 (Channel Status) is set to enable a Channel, or reset to disable a Channel.

Interrupt Mask & Status

• ADC_IMR (Interrupt Mask Register) controls the End of Conversion (EOCx) and overrun (OVREx) interrupts.
• ADC_SR (Status Register) displays the End of Conversion (EOCx) and Overrun (OVREx)
• OVRE7-OVRE0 (Overrun Error Interrupt Mask) enables the Overrun Error interrupt for Channels 0-7, if set.
• EOC7-EOC0 (End of Conversion Interrupt Mask) enables the End of Conversion interrupt for Channels 0-7, if set.
• RXBUFF (Receive Buffer Full Interrupt Disable) disables the Receive Buffer Full interrupt.
• ENDRX (End of Receive Buffer Interrupt Disable) disables the End of Receive Buffer interrupt.
• GOVRE (General Overrun Interrupt Disable) disables the General Overrun interrupt.
• DRDY (Data Ready Interrupt Disable) disables the Data Ready interrupt.

Analog Inputs

• AD0-AD7 (Analog input channels 0-7) displays the analog voltage value for each input channel.

Reference Voltage

• ADVREF (Analog reference) configures the input voltage limit for AD0-AD7.

Last Converted Data

• ADC_LCDR (Last Converted Data Register) contains the 8-bit ot 10-bit (depending on the LOWRES setting) LDATA value.
• LDATA (Last Data Converted) is the 8 or 10-bit digital output value based on the resolution setting (LOWRES).

Converted Data

• ADC_CDR-ADC_CDR7 (Converted Data) contains the 8 or 10-bit digital output value based on the resolution setting (LOWRES).

ADVREF VTREG
Data Type: float

The ADVREF VTREG sets the analog reference voltage for simulated A/D converters.

ADx VTREG
Data Type: float

The ADx VTREGs set the analog input voltages for simulated A/D converters. The ADx VTREGs represent the inputs to the analog input pins of the MCU for analog input 0, 1, 2, and so on. AD0 sets the input voltage for analog input #0, AD1 sets the input voltage for analog input #1, etc. If you have properly configured the analog inputs, the following commands (typed in the debugger's Command Window) input the voltages specified.

AD0 = 0.000  /* Analog Input 0 = 0.000 volts */
AD1 = 2.500  /* Analog Input 1 = 2.500 volts */
AD2 = 4.999  /* Analog Input 2 = 4.999 volts */

You may create a debugger signal function to periodically change the value of the A/D input. The following signal function increases the A/D Channel 1 input voltage by 0.1 volts each second.

signal void AD1_sig (void) {
float f;

for (f = 0.0; f < 5.0; f += 0.1)
  {
  swatch (1.0);                  // Delay 1 second
  AD1 = f;                       // Set AD1 Voltage
  }
}