Article Details

ID: 3767
Case Type: faq
Category: Architecture
Related To: Memory EBR/Distributed
Family: MachXO2

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Distributed_SPRAM: What is the limit of writing or reading of Single Port RAM for MachXO2 devices? Why can't I find the exact limit on how fast write or read from Single Port RAM can be done?

Description:
The maximum frequency limit value for Single Port RAM depends on the speed grade and the type of the device (that is ZE/HC/HE).
 
For example, in case of the MachXO2 Breakout Board (MachXO2-7000HE and speed grade 4), the maximum frequency limit of a Single Port RAM can be generated from the Lattice Diamond tool (Reports -> Place & Route Trace report file) by following these steps:
1. Create a new Diamond project.
2. Configure the RAM_DQ (Single Port RAM) using IPExpress, and import the IPX to the Diamond project.
3. Add the FREQUENCY timing preference for the input clock signal in the LPF constraint file.
4. Run the process flow till Place & Route Design -> Place & Route Trace.
5. Check the PAR timing report for maximum frequency limit value for a Single Port RAM.
 
Note that the exact performance may vary with device and tool version. Based on the above steps, for the MachXO2 Breakout Board with MachXO2-7000HE and speed grade 4, the maximum frequency limit value for a Single Port RAM is 150 MHz.