
www.latticesemi.com
12-1
tn1053_02.4
September 2008
Technical Note TN1053
2008 Lattice Semiconductor Corp. All Lattice trademarks, registered trademarks, patents, and disclaimers are as listed at www.latticesemi.com/legal. All other brand
or product names are trademarks or registered trademarks of their respective holders. The specifications and information herein are subject to change without notice.
Introduction
The memory in LatticeECP and LatticeEC FPGAs is built using volatile SRAM. When the power is removed,
the SRAM cells lose their contents. A supporting non-volatile memory is required to configure the device on power-
up and at any time the device needs to be updated. The LatticeECP/EC devices support a sysCONFIG interface
that provides multiple configuration modes as well as the dedicated ispJTAG port and boundary scan. The differ-
ent programming modes are listed below.
SPI
SPIX
Master Serial
Slave Serial
Master Parallel
Slave Parallel
ispJTAG (1149.1 Interface)
This technical note covers all the configuration options available for LatticeECP/EC devices.
Configuration Pins
The LatticeECP/EC devices support two types of sysCONFIG pins, dedicated and dual-purpose. The dedicated
pins are used exclusively for configuration; the dual-purpose pins are available as extra I/O pins. If a dual-purpose
pin is to be used both for configuration and as a general purpose I/O the user must adhere to the following:
The general purpose I/O (GPIO) must maintain the same direction as it has during configuration, in other words,
if the pin is an input during configuration it must remain an input as a GPIO, if an output during configuration it
must remain an output as a GPIO, if a bi-directional it must remain a bi-directional as a GPIO.
The I/O type must remain the same, in other words if the pin is a 3.3V CMOS pin (LVCMOS33) during configura-
tion it must remain a 3.3V CMOS pin as a GPIO.
The Persistent option must be set to OFF. The Persistent option can be accessed by using the Preference Editor
in ispLEVER.
The user is responsible for insuring that no internal or external logic will interfere with device configuration.
Also note, if a parallel configuration mode is not being used then one or both of the parallel port chip selects (CSN,
CS1N) must be high or tri-state during configuration.
Programmable options control the dual-purpose configuration pins. These options are controlled via a preference
in Lattice ispLEVER software, or as an HDL source file attribute. The LatticeECP/EC devices also support the
ispJTAG port for configuration, including transparent read back and JTAG testing. The following sections describe
the functionality of the sysCONFIG and JTAG pins.
Table 12-1 is provided for reference.
LatticeECP/EC sysCONFIG
Usage Guide