Testing Dual/Quad SPI Transactions with Promira Serial Platform

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As modern embedded applications demand greater bandwidth, responsiveness, and reliability, higher SPI throughput is often needed than Single SPI can efficiently provide. Dual SPI and Quad SPI (QSPI) overcome this limitation by transferring multiple bits simultaneously, making them popular choices for high-speed Flash memory and data-intensive designs.

As adoption of Dual and Quad SPI continues to grow, engineers must validate communication beyond standard flash programming workflows. This includes mode transitions, mixed I/O width transfers, device register access, and timing-sensitive fast-read commands that require precise control over how each transaction phase is constructed and executed.

The Promira Serial Platform, configured with SPI Active – Level 2 Application (Dual SPI support) or SPI Active – Level 3 Application (Dual/Quad SPI support), used in conjunction with our Control Center Serial Software’s Multi I/O SPI functionality or API, provides a practical way to interactively construct and test Dual and Quad SPI transactions, including command, address, and data phase level, directly from a PC.

Understanding Dual SPI and Quad SPI Communication

Dual SPI and Quad SPI are extensions of standard SPI that increase data throughput by using multiple data lines to transfer information in parallel. Instead of sending one bit per clock cycle as in Single SPI, Dual SPI uses two lines and Quad SPI uses four, allowing more data to be transferred in the same clock period. These modes are commonly used in high-speed embedded systems to improve performance for devices such as memory, sensors, and other SPI-based peripherals that require faster communication while maintaining a simple, low-pin-count interface.

Limits of Standard SPI Testing Approaches

Many SPI testing approaches rely on embedded firmware or flash programming utilities. While this may be effective for basic device communication, they can make it difficult to quickly construct, modify, and validate complex SPI transactions during development and debugging.

For example, engineers may need to:

• Issue commands using single-I/O mode while transferring address or data phases over Dual or Quad lanes
• Adjust dummy cycles or transaction timing
• Validate custom register access behavior
• Reproduce device-specific communication sequences

With firmware-based workflows, even small changes to transactions may require code modifications, rebuilding firmware, and redeploying to the target system before testing can continue.

Engineers often benefit from more direct control over SPI transaction phases so communication can be modified and validated interactively.

Multi-I/O SPI Transaction Structure

Some devices that support Dual and Quad SPI, particularly SPI memory devices, use transactions composed of multiple phases, where each phase may operate using a different I/O width. Rather than functioning entirely in Single, Dual, or Quad mode, these devices often combine multiple transfer formats within a single transaction.

A typical transaction includes:

• Command phase
• Address phase
• Optional dummy cycles
• Data phase

Depending on the device requirements, each phase may transfer data over one, two, or four I/O lines independently.

For example, a device may:

• Issue a command over single I/O
• Transfer the address using Dual or Quad I/O
• Return data over Quad I/O

Many fast-read and Multi-I/O memory operations follow this type of mixed-width transaction structure.

Due to this, validating Multi-I/O SPI communication often requires more than simply enabling Dual or Quad mode. Engineers must verify that each transaction phase is configured correctly, including command formatting, address length, dummy cycles, and per-phase I/O width.

Even small mismatches in transaction structure, such as incorrect dummy cycles, invalid mode configuration, or mismatched phase widths, can prevent devices from responding correctly or returning valid data.

During development and debugging, engineers may need to:

• Test different phase configurations
• Reproduce device-specific transaction sequences
• Validate transitions between Single, Dual, and Quad SPI operations
• Confirm that returned data matches expected behavior

This requires a flexible way to construct and execute custom SPI transactions with direct control over how each phase is transmitted on the bus.

Using Promira Serial Platform and Multi I/O Mode to Test Dual and Quad SPI Transactions

With a Promira Serial Platform acting as an SPI master, users can construct and execute transactions in Control Center Serial Software without requiring changes to target firmware during development.

Using Multi-I/O mode, which is only supported on the Promira Serial Platform, engineers can define the command, address, and data phases of a transaction as Single, Dual, or Quad I/O. This enables flexible construction of mixed-width SPI transactions and allows parameters to be adjusted and tested in real time during debugging.

Engineers can modify transaction structure, adjust timing parameters such as dummy cycles, validate command sequencing, and observe device responses under different Multi-I/O configurations.

Multi-I/O SPI Transactions in Control Center Serial Software

Within the Multi-I/O SPI interface, IO Mode defines how each phase of a transaction is transmitted. The command, address, and data phases can each be independently configured as Single, Dual, or Quad I/O depending on device requirements.

Key SPI parameters such as mode, bitrate, bit order, SS polarity, and slave select configuration can also be defined when constructing transactions.

A Multi-I/O SPI transaction is executed as follows:

Write (Send) Transaction

1. Assert slave select
2. Shift out command (if used)
3. Shift out address (if used)
4. Shift out data
5. Deassert slave select

Data can optionally be loaded from or saved to a binary file for repeatable testing.

Read (Receive) Transaction

1. Assert slave select
2. Shift out command (if used)
3. Shift out address (if used)
4. Shift in data from the device
5. Deassert slave select

For Dual and Quad read operations, the data lines switch to input mode during the data phase. In Single I/O mode, data is clocked out on MOSI while being received on MISO.

Multi-I/O SPI Transactions using the Promira Software API

The Promira Software API also implements Multi-I/O SPI control by allowing engineers to explicitly define the I/O width for each queued SPI operation using Single, Dual, or Quad modes.

Each transaction step can be independently configured, enabling flexible construction of mixed-width SPI sequences. Reads and writes automatically handle bus direction changes in Dual and Quad modes, allowing accurate modeling of real device behavior during validation.

Conclusion

The Promira Serial Platform, together with Control Center Serial Software, allows engineers to generate and execute Dual and Quad SPI transactions directly from a PC using Multi-I/O mode.

By defining command, address, and data phases as Single/Dual/Quad I/O engineers can quickly construct custom SPI transactions and run them immediately without firmware changes or rebuild cycles. This makes it possible to efficiently test and validate Dual and Quad SPI communication by generating and adjusting transactions and executing repeated test sequences while observing device responses in real time.

To learn more about the Promira Serial Platform and other Total Phase tools for SPI, I2C, USB, CAN, and cable testing, please contact sales@totalphase.com or request a demo.