The Actel, then Microsemi, now Microchip SmartFusion2 is a non-volatile FPGA with an embedded 166MHz ARM Cortex-M3.
All devices in the family have 32kBytes of SRAM; flash sizes are 128kB, 256kB, or 512kB depending on the model. Part numbers begin with "M2S".
I wrote this code several years ago, and re-reading my notes, the caveats for usage make it apparent why I punted on publishing the code at the time. However, it still might be of use to you as it was for me; read the details below for specifics.
Rather than put both FPGA and ARM Cortex-M3 JTAG interfaces in the same boundary chain, Microsemi created custom logic to multiplex the JTAG pins between the two. There is a JTAGSEL pin that, when driven to logic '0', selects the ARM. In the JTAGSEL = '1' mode (sometimes the only available mode on certain boards), the FPGA is selected but the ARM can also be chosen by shifting in a particular JTAG command sequence.
Confusingly, there are at least four variants of FlashPro5 devices sold by Actel/Microsemi/Microchip. Each has the same USB VID:PID, but all have different internal signal mappings that render them incompatible. So, one variant might use one of the pins as an output enable to a driver buffer, but another might use that same pin in a different manner that might cause electrical contention or erroneous behavior. One of those FlashPro5 variants is embedded in the inexpensive SmartFusion2 Maker Board.
A SEGGER J-Link can only be used with a JTAGSEL = '0' configuration. Even though the J-Link can be directed to issue the special bit sequence that works with JTAGSEL = '1', SEGGER's implementation insists on performing a JTAG test logic reset whenever connecting to the ARM target, and that action immediately reverses all that hard work.
This package was tested successfully with the following configurations:
| JTAGSEL | target | debugger | IDE |
|---|---|---|---|
| 0 | Emcraft SF2 kit | SEGGER J-Link | Rowley Crossworks for ARM |
| 0 | Emcraft SF2 kit | SEGGER J-Link | SEGGER Embedded Studio |
| 0 | Emcraft SF2 kit | Amontec JTAGkey | Rowley Crossworks for ARM |
| 1 | SmartFusion2 Maker Board | integrated Embedded FlashPro5 | Rowley Crossworks for ARM |
| 1 | Emcraft SF2 kit | Amontec JTAGkey | Rowley Crossworks for ARM |
To use the SmartFusion2 Maker Board, you must use Rowley Crossworks for ARM; SEGGER Embedded Studio is incompatible with this target. When first using the board, add a new target interface of type 'Generic FT2232 Device' and employ this configuration:
<GenericFT2232TargetInterface outputDirection="0x007B" fastMemoryAccessesEnabled="No" favorite="Yes" trstMask="0x0010" usbPid="0x2008" srstMask="0x0000" outputValue="0x0078" name="Microsemi Embedded FlashPro5" usbVid="0x1514" jtagDivider="5"/>
If using the SmartFusion2 Maker Board in Linux, you will also need a /etc/udev/rules.d file with the following content to allow Crossworks to access the JTAG interface:
# Microsemi Embedded FlashPro5
SUBSYSTEMS=="usb", ATTRS{idVendor}=="1514", ATTRS{idProduct}=="2008", MODE="0666"
In the more unusual scenario where the user has both Rowley Crossworks for ARM and SEGGER Embedded Studio installed on the same PC, at the time of writing there is a bug in SEGGER's implementation. If the J-Link is not unplugged and then plugged back in before loading the IDE, SEGGER Embedded Studio will falsely claim that the user must purchase a higher cost J-Link with flash breakpoints.