With the increasing popularity of SPI Flash memory, PROMJet added SPI Flash support in early 2004. It was the first Flash emulator to offer this feature. Since SPI Flash memory uses serial data to access Flash contents, it offers the user the ability to upgrade Flash features or Flash memory size to a higher memory capacity without changing the chip footprint on the board. Unlike parallel Flash memory that uses address and date bus that must be modified when upgrading a Flash chip, SPI Flash memory uses only a Data-In and a Data-Out signals. All address and data information is shifted serially into or out of the flash chip using these 2 signals.
PROMJet offers solid SPI Flash support. Unlike other emulators that provide a translation adapter to plug into an existing Flash emulator, PROMJet SPI engine is built inside the unit by the optional SPI interface module (OPT-SPI). A single PROMJet device can be set by the end user to run in parallel Flash or SPI Flash mode by simply choosing the appropriate bus format in the host software. Also there is no external adapter needed to translate the SPI signals into parallel Flash mode. This feature provides for better signal integrity and ease of use since the user does not have to worry about supplying the external SPI adapter with power or having the wrong setup to do SPI Flash emulation. The only adapter needed is a footprint or rewiring adapter to go from 8 or 16-pin SPI Flash footprint to the 50-pin PROMJet header. This adapter is an external plug-in that can be purchased when needed.
When replacing SPI Flash chip, PROMJet acts like one. It supports commands like, READ, WRITE, FAST-READ, JEDEC ID, CHIP ID and READ STATUS REG. The user can set up a 24-bit CHIP ID for the target system to read and identify. The JEDEC ID is set to provide the size of PROMJet emulation memory if read by the target software. PROMJet supports clock frequency up to 50MHz.
The SPI interface is fully integrated into DebugJet JTAG debug interface. This enables the user to download the firmware to the SPI flash chip and start debugging the code. Since SPI Flash is addressed via an auxiliary chip, this eases the debug process considerably.
Here are some features for PROMJet SPI Flash support.
Supports SPI clock speed up to 75MHz.
SPI support is built in PROMJet internal circuit and does not require any external adapters that would add signal delays.
Emulates all relevant SPI commands.
Supports popular SPI Flash pinouts.
Full integration with DebugJet JTAG debug interface to allow user to debug code in SPI Flash memory without programming software.
Extensive support for the GDB Debugger and the Eclipse IDE.