Peripheral Simulation
For NXP (founded by Philips) LPC2105/01 — SPI Interface
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.
Serial Peripheral Interface Dialog
The Serial Peripheral Interface Dialog allows you to view and edit
the Serial Peripheral Interface (SPI) simulator configuration.
Simulation of this interface is controlled by the following
groups:
Control Register Group
-
SPCR (Serial Peripheral Control Register) contains the
following bits that control the functions of the SPI:
-
SPIE (SPI Interrupt Enable) is set to generate an
interrupt when either the SPI Transfer Complete (SPIF) or Mode
Fault (MODF) bits set.
-
LSBF (LSB First) is set to transfer SPI data starting
with bit 0. If reset, SPI starts data transfers with bit 7.
-
MSTR (Master Mode) is set to configure the SPI as a
Master. If reset, the SPI operates in Slave mode.
-
CPOL (Clock Polarity) is set when the serial clock (SCK)
is active low. If reset, SCK is active high.
-
CPHA (Clock Phase) is set to sample data on the second
clock edge. If CPHA is reset, data sampling starts on the first
clock edge, and Slave Select (SSEL) signal determines the start and
end of the data transfer cycle.
Status Register Group
-
SPSR (SPI Status Register) monitors the SPI status. It
contains the following read-only bits:
-
SPIF (Data Transfer Complete) is set when the SPI
completes a data transfer operation. This bit clears after this
register and the data register (SPDR) are read.
-
WCOL (Write Collision) is set when data is written to
the SPI data register while a SPI data transfer is in
progress.
-
ROVR (Read Overrun) is set when the SPI receives data
before it's read buffer is empty.
-
MODF (Mode Fault) is set when the Slave Select (SSEL)
goes active and the SPI is configured as a master.
-
ABRT (Slave Abort) is set when the Slave Select (SSEL)
signal goes inactive before a data transfer completes.
Clock Counter Group
-
SPCCR (SPI Clock Counter Register) controls the SPI
clock rate when the SPI is configured as a master. This value is
the number of PCLK cycles that make up 1 SPI clock.
-
Master Clock is the SPI clock value (SCK) based on the
SPCCR setting.
Data Register Group
-
SPDR (SPI Data Register) contains the either the data to
be transmitted or the data received. In Master mode, writing to
this register starts data transfer.
Slave Select Group
-
SSEL# Pin (Slave Select) is the signal level at the
slave select pin.
Interrupt Register Group
-
SPINT (SPI Interrupt Register) contains the SPI
interrupt flag setting.
-
SPI Interrupt (SPI Interrupt Flag) is set by the SPI
interface to generate an SPI interrupt.
SPI_IN VTREG
Data Type: unsigned char
The SPI_IN VTREG contains a byte which is received via the
MCU SPI (Serial Peripheral Interface) port on the next SPI transfer.
You may use this VTREG in a simulation script. For example:
signal void spi_func (void) {
while (1) {
wwatch (SPI_OUT);
printf ("SPI_OUT: %2.2X\n", (unsigned) SPI_OUT);
SPI_IN = SPI_OUT + 1;
}
}
This signal function returns the SPI byte send plus 1 on the next
SPI transfer.
SPI_OUT VTREG
Data Type: unsigned char
The SPI_OUT VTREG contains a byte output via the MCU SPI
(Serial Peripheral Interface) port. When your simulated program sends
a byte via SPI, the SPI_OUT VTREG is set with the value
output. You may monitor this VTREG in a simulation script. For
example:
signal void spi_watcher (void) {
while (1) {
wwatch (SPI_OUT);
printf ("SPI_OUT: %2.2X\n", (unsigned) SPI_OUT);
}
}