By Adam Taylor

In conventional SoC design, we would implement our module using RTL and create (hopefully) a test bench to ensure our RTL functions as intended against the specification. This test bench will of course be used to test the module’s boundary and corner cases.

When we develop algorithms in high-level software, we may develop a test harness which itself calls the software function we are developing, subjects it to inputs, and checks that the function behaves as expected. In many ways this is similar to an RTL test bench, however it is typically quicker to execute a piece of compiled code than it is to run an RTL simulation. Checking functions in software allows us to demonstrate that we have implemented the correct algorithm (and implemented the algorithm correctly) prior to accelerating the function in hardware.

When using SDSoC to accelerate functions, we need to consider other aspects that may cause an issue when we accelerate them. These issues can be grouped into three overarching groups:

Build Errors

Run-Time Errors

Performance Errors

Build errors occur with SDSoC as the tool attempts to create the executables and boot files. The cause of the error will be reported within the log and report files. Build-error causes include typos, syntax errors and failure to follow coding guidelines, and implementation issues. Implementation issues include aspects such as Vivado HLS or Vivado not being able to achieve the desired timing. If this is the case, you must again look at the defined clock frequencies and optimization options.

A final-build error can occur when the accelerated design does not fit within the PL side of the selected Zynq device. If this is the case all is not lost. You can look at accelerating fewer functions or modifying your hardware optimizations to produce more compact implementations. For example, you can prohibit loop unrolling.

Runtime errors are very similar to those experienced in traditional software development (e.g. incorrect results or premature completion of the program). Of course these problems can be debugged using the profiler and debugger within SDSoC. There is however anther issue which can occur and that is the program “hanging.” This occurs when streaming data transfers are mismatched between the producer and the consumer. A “hang” occurs when the producer has stopped producing data while the consumer is waiting for more data. Here’s an example:

The code snippet above shows a simple example which will implement as a streaming connection and hang when executed. Of course the reason is very straightforward. A simple “<” operator in place of a “<=” operator results in only 19 reads while the consumer is expecting 20 reads and will hang waiting for the 20th.

Performance issues arise when there are problems with the algorithm we have accelerated or with the time taken to transfer data to or from the accelerated function. The next blog in this series will look at how we can debug such applications.

Incidentally I am talking at the Embedded Systems Conference in Santa Clara this week on using lessons learned from VHDL/FPGA space development here on earth. If you see me about please come over and say hello.

Note: Xilinx has announced the public access release of the SDSoC development environment for Zynq SoCs and MPSoCs.



Now, you can have convenient, low-cost Kindle access to the first year of Adam Taylor’s MicroZed Chronicles for a mere $7.50. Click here.

Please see the previous entries in this MicroZed Chronicles series by Adam Taylor:

Adam Taylor’s MicroZed Chronicles Part 91: More on High-Level Synthesis and SDSoC, Part 7

Adam Taylor’s MicroZed Chronicles Part 90: Introduction to High-Level Synthesis and SDSoC, Part 6

Adam Taylor’s MicroZed Chronicles Part 89: SDSoC Optimization, Part 5

Adam Taylor’s MicroZed Chronicles Part 88: SDSoC Part 4—a look under the hood

Adam Taylor’s MicroZed Chronicles Part 87: Getting SDSoC up and running Part 3

Adam Taylor’s MicroZed Chronicles Part 86: Getting SDSoC up and running

Adam Taylor’s MicroZed Chronicles Part 85: SDSoC—the first instalment

Adam Taylor’s MicroZed(ish) Chronicles Part 84: Simple Communication Interfaces Part 4

Adam Taylor’s MicroZed(ish) Chronicles Part 83: Simple Communication Interfaces Part 3

Adam Taylor’s MicroZed(ish) Chronicles Part 82: Simple Communication Interfaces Part 2

Adam Taylor’s MicroZed(ish) Chronicles Part 81: Simple Communication Interfaces

Adam Taylor’s MicroZed Chronicles Part 80: LWIP Stack Configuration

Adam Taylor’s MicroZed Chronicles Chronicles Part 79: Zynq SoC Ethernet Part III

Adam Taylor’s MicroZed Chronicles Chronicles Part 78: Zynq SoC Ethernet Part II

Adam Taylor’s MicroZed Chronicles Microzed Chronicles Part 77 – Introducing the Zynq SoC’s Ethernet

Adam Taylor’s MicroZed Chronicles Part 76: Constraints for Relatively Placed Macros

Adam Taylor’s MicroZed Chronicles, Part 75: Placement Constraints – Pblocks

Adam Taylor’s MicroZed Chronicles, Part 73: Physical Constraints

Adam Taylor’s MicroZed Chronicles, Part 73: Working with other Zynq-Based Boards

Adam Taylor’s MicroZed Chronicles, Part 72: Multi-cycle Constraints

Adam Taylor’s MicroZed Chronicles, Part 70: Constraints—Clock Relationships and Avoiding Metastability

Adam Taylor’s MicroZed Chronicles, Part 70: Constraints—Introduction to timing and defining a clock

Adam Taylor’s MicroZed Chronicles Part 69: Zynq SoC Constraints Overview

Adam Taylor’s MicroZed Chronicles Part 68: AXI DMA Part 3, the Software

Adam Taylor’s MicroZed Chronicles Part 67: AXI DMA II

Adam Taylor’s MicroZed Chronicles Part 66: AXI DMA

Adam Taylor’s MicroZed Chronicles Part 65: Profiling Zynq Applications II

Adam Taylor’s MicroZed Chronicles Part 64: Profiling Zynq Applications

Adam Taylor’s MicroZed Chronicles Part 63: Debugging Zynq Applications

Adam Taylor’s MicroZed Chronicles Part 62: Answers to a question on the Zynq XADC

Adam Taylor’s MicroZed Chronicles Part 61: PicoBlaze Part Six

Adam Taylor’s MicroZed Chronicles Part 60: The Zynq and the PicoBlaze Part 5—controlling a CCD

Adam Taylor’s MicroZed Chronicles Part 59: The Zynq and the PicoBlaze Part 4

Adam Taylor’s MicroZed Chronicles Part 58: The Zynq and the PicoBlaze Part 3

Adam Taylor’s MicroZed Chronicles Part 57: The Zynq and the PicoBlaze Part Two

Adam Taylor’s MicroZed Chronicles Part 56: The Zynq and the PicoBlaze

Adam Taylor’s MicroZed Chronicles Part 55: Linux on the Zynq SoC

Adam Taylor’s MicroZed Chronicles Part 54: Peta Linux SDK for the Zynq SoC

Adam Taylor’s MicroZed Chronicles Part 53: Linux and SMP

Adam Taylor’s MicroZed Chronicles Part 52: One year and 151,000 views later. Big, Big Bonus PDF!

Adam Taylor’s MicroZed Chronicles Part 51: Interrupts and AMP

Adam Taylor’s MicroZed Chronicles Part 50: AMP and the Zynq SoC’s OCM (On-Chip Memory)

Adam Taylor’s MicroZed Chronicles Part 49: Using the Zynq SoC’s On-Chip Memory for AMP Communications

Adam Taylor’s MicroZed Chronicles Part 48: Bare-Metal AMP (Asymmetric Multiprocessing)

Adam Taylor’s MicroZed Chronicles Part 47: AMP—Asymmetric Multiprocessing on the Zynq SoC

Adam Taylor’s MicroZed Chronicles Part 46: Using both of the Zynq SoC’s ARM Cortex-A9 Cores

Adam Taylor’s MicroZed Chronicles Part 44: MicroZed Operating Systems—FreeRTOS

Adam Taylor’s MicroZed Chronicles Part 43: XADC Alarms and Interrupts

Adam Taylor’s MicroZed Chronicles MicroZed Part 42: MicroZed Operating Systems Part 4

Adam Taylor’s MicroZed Chronicles MicroZed Part 41: MicroZed Operating Systems Part 3

Adam Taylor’s MicroZed Chronicles MicroZed Part 40: MicroZed Operating Systems Part Two

Adam Taylor’s MicroZed Chronicles MicroZed Part 39: MicroZed Operating Systems Part One

Adam Taylor’s MicroZed Chronicles MicroZed Part 38 – Answering a question on Interrupts

Adam Taylor’s MicroZed Chronicles Part 37: Driving Adafruit RGB NeoPixel LED arrays with MicroZed Part 8

Adam Taylor’s MicroZed Chronicles Part 36: Driving Adafruit RGB NeoPixel LED arrays with MicroZed Part 7

Adam Taylor’s MicroZed Chronicles Part 35: Driving Adafruit RGB NeoPixel LED arrays with MicroZed Part 6

Adam Taylor’s MicroZed Chronicles Part 34: Driving Adafruit RGB NeoPixel LED arrays with MicroZed Part 5

Adam Taylor’s MicroZed Chronicles Part 33: Driving Adafruit RGB NeoPixel LED arrays with the Zynq SoC

Adam Taylor’s MicroZed Chronicles Part 32: Driving Adafruit RGB NeoPixel LED arrays

Adam Taylor’s MicroZed Chronicles Part 31: Systems of Modules, Driving RGB NeoPixel LED arrays

Adam Taylor’s MicroZed Chronicles Part 30: The MicroZed I/O Carrier Card

Zynq DMA Part Two – Adam Taylor’s MicroZed Chronicles Part 29

The Zynq PS/PL, Part Eight: Zynq DMA – Adam Taylor’s MicroZed Chronicles Part 28

The Zynq PS/PL, Part Seven: Adam Taylor’s MicroZed Chronicles Part 27

The Zynq PS/PL, Part Six: Adam Taylor’s MicroZed Chronicles Part 26

The Zynq PS/PL, Part Five: Adam Taylor’s MicroZed Chronicles Part 25

The Zynq PS/PL, Part Four: Adam Taylor’s MicroZed Chronicles Part 24

The Zynq PS/PL, Part Three: Adam Taylor’s MicroZed Chronicles Part 23

The Zynq PS/PL, Part Two: Adam Taylor’s MicroZed Chronicles Part 22

The Zynq PS/PL, Part One: Adam Taylor’s MicroZed Chronicles Part 21

Introduction to the Zynq Triple Timer Counter Part Four: Adam Taylor’s MicroZed Chronicles Part 20

Introduction to the Zynq Triple Timer Counter Part Three: Adam Taylor’s MicroZed Chronicles Part 19

Introduction to the Zynq Triple Timer Counter Part Two: Adam Taylor’s MicroZed Chronicles Part 18

Introduction to the Zynq Triple Timer Counter Part One: Adam Taylor’s MicroZed Chronicles Part 17

The Zynq SoC’s Private Watchdog: Adam Taylor’s MicroZed Chronicles Part 16

Implementing the Zynq SoC’s Private Timer: Adam Taylor’s MicroZed Chronicles Part 15

MicroZed Timers, Clocks and Watchdogs: Adam Taylor’s MicroZed Chronicles Part 14

More About MicroZed Interrupts: Adam Taylor’s MicroZed Chronicles Part 13

MicroZed Interrupts: Adam Taylor’s MicroZed Chronicles Part 12

Using the MicroZed Button for Input: Adam Taylor’s MicroZed Chronicles Part 11

Driving the Zynq SoC's GPIO: Adam Taylor’s MicroZed Chronicles Part 10

Meet the Zynq MIO: Adam Taylor’s MicroZed Chronicles Part 9

MicroZed XADC Software: Adam Taylor’s MicroZed Chronicles Part 8

Getting the XADC Running on the MicroZed: Adam Taylor’s MicroZed Chronicles Part 7

A Boot Loader for MicroZed. Adam Taylor’s MicroZed Chronicles, Part 6

Figuring out the MicroZed Boot Loader – Adam Taylor’s MicroZed Chronicles, Part 5

Running your programs on the MicroZed – Adam Taylor’s MicroZed Chronicles, Part 4

Zynq and MicroZed say “Hello World”-- Adam Taylor’s MicroZed Chronicles, Part 3

Adam Taylor’s MicroZed Chronicles: Setting the SW Scene

Bringing up the Avnet MicroZed with Vivado