1263 - Can the PROGRAMN pin be held low for a period of time during power-up to prevent the FPGA from configuring?
Yes, PROGRAMN pin can be used to hold FPGA from configuring.
The are cases where user is using SPI programming mode and would like to control the exact time to begin configuration with PROGRAMN pin.
Lattice FPGA enter configuration mode when one of three condition happens.
1. Power is applied to the chip
2. PROGRAMN pin is toggled low then high
3. or when a JTAG Refresh instruction is issued
A high to low signal applied to PROGRAMN takes the device out of user mode and sets it into configuration mode. The low to high transition will initiate the configuration process. The PROGRAMN pin can be used to trigger configuration at any time.
Related Articles
1323 - Is PROGRAMN pin independent of JTAG programming operations? <br>
The PROGRAMN pin does not affect the JTAG state machine or boundary scan cells. However, the PROGRAMN pin does clear the SRAM configuration memory of the device. Because of this, a logic low signal on PROGRAMN pin at any time during JTAG ...
2125 - What is the device programming time of a Lattice FPGA?
Solution: The time to program a Lattice FPGA is dependent on several factors including configuration mode, programming speed, and device size. Some configuration modes and methods are faster than others. The complete configuration time inherently ...
1681 - MachXO2: What happens if the PROGRAMN pin is toggled before device configuration is completed when in SPI configuration mode?
The PROGRAMN pin is used by the MachXO2 configuration logic to initiate programming of the device. Generally this pin is held inactive high during configuration. In the MachXO2, SPI configuration will restart when PROGRAMN is toggled during ...
4729 - MachXO2: Why is it not recommended to control/toggle the PROGRAMN pin to trigger reconfiguration from its own GPIO?
It is not recommended to control the PROGRAMN pin from its own GPIO because the MachXO2 device's GPIO might permanently pull down the PROGRAMN pin. Thus, the device will always be held in reconfiguration state, and will not communicate or be erased ...
2990 - MachXO2:<div>If MachXO2 is in the Feature Row Hardware Default Mode state (erased state) and PROGRAMN is held LOW, then would the device block the JTAG port from accessing the internal flash, or block the access to other devices in the JTAG chain?
Definition: No, the device will not block the JTAG from either accessing the internal Flash or accessing the other devices in the JTAG chain. The PROGRAMN pin is transition sensitive, and not level sensitive.