A3P-MRAM Real-time I/O

A3P-MRAM - Real-time I/O
Description of USB access to the FPGA

Introduction
Capabilities
Example
Sample projects
Ordering information

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Introduction

The A3P-MRAM module features multi-function USB controller. This controller is used for programming of the FPGA. It can be also used as a JTAG emulator for different controllers programmed into the FPGA. Currently supported are SL8051 (Silicon Laude) and Core8051 (Actel).

The USB controller can be also used to transfer data from/to the PC in real-time. This page illustrates example implementation of such a transfer for both FPGA and PC.

Capabilities

The data transfer rates are in 100-200 KBytes/second range. If faster data transfer is needed, the advanced SB-USB2 can be used. It will allow transferring up to 10 MBytes/s, but it will use 11 pins out of the 41 pins available for I/O on the A3P-MRAM module.

The USB microcontroller is using 11 dedicated signals to transfer data. None of the module I/O pins are used for data transfer. The eight bit bus is multiplexed between address and data with the ALE signal. Read and write operations are accomplished with -RD and -WR strobes. This allows to access up to 256 8-bit registers.

Example

Sample read transfer of 16-bit data with 16-bit address

Sample write transfer of 16-bit data with 16-bit address

On the waveforms above sample read/write data transfers are illustrated. Each transfer sets 16-bit address to read or write 16-bits of data in the MRAM device. Each transaction consists of two strobes writing low and high byte of the 16-bit address to be accessed, followed by two strobes reading/writing 8-bits of data. Each strobe sets the engine address lines decoded by the logic inside the FPGA.

The above waveforms were captured with the 40 MHz Logic Analyzer integrated in the SB-USB2 JTAG/OnCE emulator.

Sample projects

Actel's Libero project a3pmram1000.zip (721 KB) has an example of the FPGA logic for the A3P1000 device, which supports described above data transfer.

Microsoft Visual Studio 6 project a3pm_io.zip (217 KB) has an example console application illustrating 8-bit register access and 16-bit data access. This example illustrates also main functions used to open and close connection to the A3P-MRAM module over the PC's USB port.

Ordering Information

A3P-MRAM-1000	Development module with Actel A3P1000-FG256 and Freescale MRAM
A3P-MRAM-250	Development module with Actel A3P250-FG256 and Freescale MRAM
A3P-NM-1000	Development module with Actel A3P1000-FG256 and no MRAM installed
A3P-NM-250	Development module with Actel A3P250-FG256 and no MRAM installed
A3P-MRAM-BASE	Base board for A3P-MRAM module
A3P-MRAM-KIT	Development kit: A3P-MRAM-1000, A3P-MRAM-BASE, BoxViewIDE

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