Lattice Semiconductor MachXO2 Programming And Configuration Usage Manual page 32

JTAG Port
The JTAG_PORT preference allows you to decide how the JTAG configuration port pins operate when the
MachXO2 device is in user mode. There are two states the JTAG_PORT can be set to:
• ENABLE – In this mode the JTAG I/O are dedicated and provide an IEEE 1149.1 JTAG interface
• DISABLE – In this mode the JTAG I/O pins are controlled dynamically using the JTAGENB pin
The JTAGENB pin is only available when the JTAG_PORT is in the DISABLE state. JTAGENB, when asserted high,
makes the four JTAG I/O act as an IEEE 1149.1 JTAG port. JTAGENB driven low causes the four I/O to be available
for use as general purpose I/O.
Lattice recommends designing so that the JTAG port can be accessed in the event reprogramming the MachXO2
disables your primary configuration port.
Slave SPI Port
The SLAVE_SPI_PORT allows you to preserve the Slave SPI configuration port after the MachXO2 device enters
user mode. There are two states to which the SLAVE_SPI_PORT preference can be set:
• ENABLE – This setting preserves the SPI port I/O when the MachXO2 device is in user mode. When the pins
are preserved, an external SPI master controller can interact with the configuration logic. The preference also
prevents you from over-assigning I/O to the port pins.
• DISABLE – This setting disconnects the SPI port pins from the configuration logic. By itself it does not make the
port pins general purpose I/O. Both the SLAVE_SPI_PORT and MASTER_SPI_PORT must be in the DISABLE
state for the SPI port pins to be general purpose I/O.
The SLAVE_SPI_PORT can be enabled at the same time as the MASTER_SPI_PORT. It is necessary to guaran-
tee that the internal SPI master controller not perform SPI transactions at the same time as an external SPI master.
It is your responsibility to prevent two SPI masters from operating simultaneously.
Master SPI Port
The MASTER_SPI_PORT allows you to preserve the SPI configuration port after the MachXO2 device enters user
mode. There are three states to which the MASTER_SPI_PORT preference can be set:
• ENABLE – This setting preserves the SPI port I/O when the MachXO2 is in user mode. This preference makes
External or Dual Boot configuration modes active. Using this preference in combination with CONFIGURATION =
EXTERNAL enables external boot mode. This preference in combination with CFG, CFG_EBRUFM, CFGUFM
enables Dual Boot mode. After entering user mode, the SPI controller in the EFB has access to the SPI port for
performing SPI bus transactions. The preference also prevents you from over-assigning I/O to the port pins.
• EFB_USER – This setting preserves the SPI port I/O when the MachXO2 is in user mode. After entering user
mode, the SPI controller in the EFB has access to the SPI port for performing SPI bus transactions. The prefer-
ence also prevents you from over-assigning I/O to the port pins.
• DISABLE – This setting disconnects the SPI port pins from the configuration logic. By itself it does not make the
port pins general purpose I/O. Both the SLAVE_SPI_PORT and MASTER_SPI_PORT must be in the DISABLE
state for the SPI port pins to be general purpose I/O.
The MASTER_SPI_PORT can be enabled at the same time as the SLAVE_SPI_PORT. It is necessary to guaran-
tee that the internal SPI Master controller not perform SPI transactions at the same time as an external SPI Master.
It is your responsibility to prevent two SPI masters from operating simultaneously.
MachXO2 Programming and Configuration Usage Guide
32