Peripheral Simulation

For Atmel AT91SAM7S128 — Universal Synchronous/Asynchronous Receiver/Transmitter 1

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.

USART 1 Dialog

The USART 1 Dialog configures USART 1. A USART transfers serial data to and from external devices and the ARM controller. The USART can be configured in a variety of ways to suit the external serial device.

Control

• US1_CR (USART 1 Control Register) displays the combined control information for the following:
• RXEN (Receiver Enable) enables the receiver.
• TXEN (Transmitter Enable) enables the transmitter.
• RXDIS (Receiver Disable) disables the receiver.
• TXDIS (Transmitter Disable) disables the transmitter.
• RSTRX (Reset Receiver) resets the receiver.
• RSTTX (Reset Transmitter) resets the transmitter.
• RSTSTA (Reset Status Bits) resets the Parity Error (PARE), Framing Error (FRAME), Overrun Error (OVRE) and Break Received (RXBRK) status bits.
• SENDA (Send Address) sets the address bit with the next character written (multi-drop mode only).
• RSTIT (Reset Iterations) resets the Iteration status.
• STTTO (Start Time-out) restarts the wait time-out for a new character.
• RSTNACK (Reset Non Acknowledge) resets the Non Acknowledge status.
• RETTO (Reload and Start Time-out) restarts the receiver time-out counter.
• STTBRK (Start Break) generates a break condition after the next character is sent.
• STPBRK (Stop Break) cancels a break condition.
• DTREN (Data Terminal Ready Enable) drives the DTR pin to 0.
• DTRDIS (Data Terminal Ready Disable) drives the DTR pin to 1.
• RTSEN (Request to Send Enable) drives the RTS pin to 0.
• RTSDIS (Request to Send Disable) drives the RTS pin to 1.

Mode

• US1_MR (Mode Register) contains the USART Mode settings which is determined by settings of other controls in this group.
• MODE (USART Mode) configures the USART for normal, RS485, hardware handshake, modem, ISO7816 Protocol: T=0, ISO7816 Protocol: T=1 or IrDA mode.
• CHMODE (Channel Mode) selects normal, loopback, echo or remote loopback pin configurations.
• SYNC (Synchronous Mode Select) enables Synchronous mode.
• CHRL (Character Length) selects the number of bits per character.
• NBSTOP (Number of Stop Bits) selects the number of stop bits to be sent with each character.
• PAR (Parity Type) selects the generation of even, odd or no parity bits, mark or space, or multi-drop mode.
• Mode 9 (9-bit Mode) is set to use 9 data bits for character length. If reset, CHRL determines character length.
• MBSF (Most Significant Bit First) is set to send or receive the most significant bit first. If reset, the least significant bit first is sent or expected.
• CLKO (Clock Output Select) when set, drives the SCK pin if the external clock is not selected.
• USCLKS (Clock Selection) selects clock source and type.
• MAX_ITERATION (Maximum Number of Iterations) configures the maximum number of iterations when using mode ISO7816, protocol T=0.
• OVER (Oversampling Mode) is set to use 8x oversampling. If reset, the USART uses 16x oversampling.
• FILTER (Infrared Line Receive Filter) is set to enable the USART's three-sample filter.
• INACK (Inhibit Non Acknowledge) is set to suppress NACK generation.
• DSNACK (Disable Successive NACK) is set to count successive parity errors up to the MAX_ITERATION value. If that value is reached, the ITERATION bit is set.

Baudrate Generator & FI DI Ratio

• US1_BRGR (Baud Rate Generator Register) holds the Clock Divisor (CD) value.
• CD (Clock Divisor) contains the value divided into the clock that determines the baud rate.
• Baudrate displays the baud rate calculated by the USART.
• US1_FIDI (FI DI Register) contains the clock frequency division factor (FI) over the bit-rate adjustment factor (DI) for ISO7816 mode.
• US1_FIDI_RATIO (FI Over DI Ratio) contains the value divided into the SCK to determine the IOS7816 baudrate.

Receiver Time-out & Transmitter Time-guard

• US1_RTOR (Receiver Time-out Register) holds the receiver time-out value.
• TO (Time Out) sets the time-out counter value used with the Start Time-out command.
• US1_TTGR (Transmitter Time-guard Register) holds the transmitter time guard value.
• TG (Time-guard) sets the length of time TXD is inactive after each character.

Receiver & Transmitter

• US1_RHR (Receiver Holding Register) contains the RXCHR character.
• RXCHR (Received Character) holds the last character received.
• US1_THR (Transmitter Holding Register) contains the TXCHR character.
• TXCHR (Character to be Transmitted) holds the next character to be transmitted.

Number of Errors and IrDA Filter

• US1_NER (Number of Errors Register) contains the NB_ERRORS value.
• NB_ERRORS (Number of Errors) contains the total number of errors that occurred during an ISO7816 data transfer. This register is cleared when read.
• US1_IF (IrDA Filter) contains the IRDA_FILTER value.
• IRDA_FILTER (IrDA Filter) contains the 8-bit down counter value used for demodulation of the received signal.

Interrupt Mask & Channel Status

• US1_IMR (Interrupt Mask Register) holds the masking bits for all of the internal peripheral interrupts.
• US1_CSR (Channel Status Register) holds the composite status for the USART channel.
• CTS (Clear to Send pin) displays the CTS pin status.
• DCD (Data Carrier Detect pin) displays the DCD pin status.
• DSR (Data Set Ready pin) displays the DSR pin status.
• RI (Ring Indicator pin) displays the RI pin status.
• CTSIC (Clear to Send Input Change Flag) is set if at least 1 input change on CTS is detected.
• DCDIC (Data Carrier Detect Input Change Flag) is set if at least 1 input change on DCD is detected.
• DSRIC (Data Set Ready Input Change Flag) is set if at least 1 input change on DSR is detected.
• RIIC (Ring Indicator Input Change Flag) is set if at least 1 input change on RI is detected.
• NACK (Non Acknowledge Flag) is set if at least one NACK is detected.
• RXBUFF (Receive Buffer Full) is set if the Buffer Full signal from the PDC is active.
• TXBUFF (Transmit Buffer Full) is set if the Buffer Empty signal from the PDC is active.
• ITERATION (Iteration Flag) set if more than the maximum number of parity errors has occurred.
• TXEMPTY (Transmitter Empty) set if there are no characters in the transmitter hold register(US1_THR).
• TIMEOUT (Receiver Time-out) set if a Start Time-out counter has elapsed.
• PARE (Parity Error) set if the controller detects at least 1 false parity bit since the last Reset Status Bits command (RSTSTA).
• FRAME (Framing Error) set if the controller detects a framing error since the last Reset Status Bits command (RSTSTA).
• OVRE (Overrun Error) set if the controller detects an overrun condition since the last Reset Status Bits command (RSTSTA).
• ENDTX (End of Transmitter Transfer) is set if the End of Transmitter signal is active.
• ENDRX (End of Receiver Transfer) is set if the End of Receiver signal is active.
• RXBRK (Break Received/End of Break) is set if the USART receives a break since the last Reset Status Bits command (RSTSTA).
• TXRDY (Transmitter Ready) set if the transmit hold register (US1_THR) is empty and there is no break request pending.
• RXRDY (Receiver Ready) set when the USART receives at least 1 character and the receiver hold register (US1_RHR) is not empty.

Modem Lines

• RTS1 (Request to Send) displays the RTS pin status.
• CTS1 (Clear to Send) displays the CTS pin status.
• DTR1 (Data Terminal Ready) displays the DTR pin status.
• DSR1 (Data Set Ready) displays the DSR pin status.
• DCD1 (Data Carrier Detect) displays the DCD pin status.
• RI1 (Ring Indicator) displays the RI pin status.

SxIN VTREG
Data Type: unsigned int

The SxIN VTREG represents the serial input of the simulated microcontroller. Values you assign to SxIN are input to the serial channel 0, 1, 2, and so on. You may assign input using the command window. For example,

S0IN='A'

causes the simulated microcontroller serial input 0 to receive the ASCII character A. If you want to use the SxIN VRTEG to simulate reception of multiple characters, you must be sure to delay for at least one character time between successive assignments to SxIN. This may be done using a signal function. For example:

signal void send_cat (void) {
swatch(0.01);  /* Wait 1/100 seconds */
S0IN='C';      /* Send a C */
swatch(0.01);
S0IN='A';
swatch(0.01);
S0IN='T';
}

You may use the SxIN VTREG to input data (5-9 bits), parity, frame error and break condition. SxIN Format (16-bit Register)

• Bits 0-8: Data (5, 6, 7, 8 or 9 bit)
• Bit 9: Parity bit Value
• Bit 10: Parity bit Presence (0=Not present, 1=Present)
• Bit 11: Invalid Stop bit (0=Normal, 1=Invalid)
• Bit 12: End of Break

For example:

S0IN=0x0074 // Data = 0x74,  No Parity bit
S0IN=0x0174 // Data = 0x174, No Parity bit
S0IN=0x0474 // Data = 0x74,  Parity bit = 0
S0IN=0x0674 // Data = 0x74,  Parity bit = 1
S0IN=0x0874 // Data = 0x74,  No Parity bit
            // Invalid Stop bit - Frame Error
S0IN=0x0800 // Break Condintion
S0IN=0x1000 // End of Break Condition

In addition to the SxIN VRTEG, the serial window allows you to input serial characters by simply typing. Serial characters that are transmitted byt the simulated microcontroller appear in the serial window.

SxOUT VTREG
Data Type: unsigned int

The SxOUT VTREG represents the serial output from the simulated serial port 0, 1, and so on. Whenever the simulated serial port transmits a character, the value transmitted is automatically assigned to SxOUT (which is read-only). You may read the value of SxOUT to determine the character transmitted by your simulated program. For example,

S0OUT

outputs the value of the last character transmitted by serial port 0.

SxOUT Format (16-bit Register)

• Bits 0-8: Data (5, 6, 7, 8 or 9 bits)
• Bit 9: Parity bit Value
• Bit 10: Parity bit Presence (0=Not present, 1=Present)
• Bit 11: Invalid Stop bit (0=Normal, 1=Invalid)
• Bit 12: End of Break

For example:

S0OUT & 0x01FF // Data
S0OUT & 0x0400 // Parity bit is present
S0OUT & 0x0200 // Parity bit value (0=0, 0x0200=1)

Note that you cannot assign values to the SxOUT VTREGs. You may use the SxOUT VTREG in a script to process transmitted data. For example,

signal void s0out_sig (void) {
while (1)
  {
  wwatch(S0OUT);     /* wait for something in S0OUT */
  printf ("Transmitted a %2.2X\n", (unsigned) S0OUT);
  }
}

SxTIME VTREG
Data Type: unsigned char

The SxTIME VTREG allows you to control the timing of the simulated serial port 0, 1, and so on.

• A value of 1 (which is the default) indicates that the serial port timing is identical to the target hardware. Use this value when you want to see the effects of baud rate on the serial port I/O.
• A value of 0 indicates that all serial input and output occur instantaneously. Use this value when you don't care about any baud rate effects or when you want serial output to be fast.

For example:

S0TIME = 0   /* Set Serial Port 0 for FAST timing */
S0TIME = 1   /* Set Serial Port 0 for accurate timing */