EM Software Development Platform¶

Info

Please refer to board's documentation for detailed information about how to setup the board for initial operation.

Refer Getting OpenOCD and Using OpenOCD for details about installing and using OpenOCD.

Preface¶

EM SDP board is shipped with with FPGA chip. There is a number of ARC EM images available for writing to it. Here is a list of those images and corresponding target options for GCC:

CPU image	GCC targets options
EM11D	`-mcpu=em4_fpuda -mmpy-option=6 -mfpu=fpuda_all`
EM9D	`-mcpu=em4_fpuda -mmpy-option=6 -mfpu=fpuda_all`
EM7D	`-mcpu=em4_dmips -mno-div-rem -mmpy-option=3 -mfpu=fpuda_all`
EM7D ESP	`-mcpu=em4_fpuda -mmpy-option=6 -mbarrel-shifter -mfpu=fpuda_all`
EM6	`-mcpu=em4_dmips -mno-div-rem -mmpy-option=3 -mfpu=fpuda_all`
EM5D	`-mcpu=em4_fpuda -mmpy-option=6 -mfpu=fpuda_all`
EM4	`-mcpu=em4_fpuda -mno-div-rem -mmpy-option=3 -mfpu=fpuda_all`

In this guide we use EM11D core as an example. Also, the version of the EM SDP firmware is considered to be 1.0 or 1.1.

Building an Application¶

Consider a simple application with name main.c:

#include <stdio.h>

int main()
{
    printf("Hello, World!\n");
    return 0;
}

Build the application:

arc-elf32-gcc -mcpu=em4_fpuda -mmpy-option=6 -mfpu=fpuda_all \
              -specs=emsdp1.1.specs main.c -o main.elf

-specs=emsdp1.1.specs sets a proper memory map and links the application with additional startup code and UART library for input/output operations.

Here is a list of all available specs files:

Specs file	EM SDP firmware	Description
`emsdp1.1.specs`	1.0, 1.1	Code and data are placed in ICCM and DCCM
`emsdp1.1_ram.specs`	1.0, 1.1	Code and data are placed in RAM
`emsdp1.2.specs`¹	1.2	Code and data are placed in ICCM and DCCM
`emsdp1.2_ram.specs`	1.2	Code and data are placed in RAM

Running an Application¶

Follow Using OpenOCD guide and start OpenOCD with snps_em_sk_v2.3.cfg configuration file. Here is a possible output:

$ openocd  -f board/snps_em_sk_v2.3.cfg
Open On-Chip Debugger 0.12.0+dev-gffa52f0e0 (2023-08-02-10:41)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : ftdi: if you experience problems at higher adapter clocks, try the command "ftdi tdo_sample_edge falling"
Info : clock speed 10000 kHz
Info : JTAG tap: arc-em.cpu tap/device found: 0x200044b1 (mfg: 0x258 (ARC International), part: 0x0004, ver: 0x2)
Info : starting gdb server for arc-em.cpu on 3333
Info : Listening on port 3333 for gdb connections

Then connect to the server using GDB:

$ arc-elf32-gdb -quiet main.elf
(gdb) target remote :3333

# Increase timeout, because OpenOCD sometimes can be slow
(gdb) set remotetimeout 15

# Load application into target
(gdb) load

# Go to start of main function
(gdb) tbreak main
(gdb) continue

# Resume with usual GDB commands
(gdb) step
(gdb) next

# Go to end of the application
(gdb) tbreak exit
(gdb) continue

# For example, check exit code of application
(gdb) info reg r0

Connecting to the Serial Terminal¶

Follow the corresponding guide for ARC EM Software Development Platform.

The memory map for EM SDP 1.2 firmware differs from the memory map for EM SDP 1.0 and 1.1. That is why there are different specs files. ↩