Support Question of the Week: How Do I Use the Cheetah SPI Host Adapter with a 1.8V Flash Device and Adjust the Timing?

I just started using your CheetahTM SPI Host Adapter and high speed flash sockets to program 1.8V Micron flash devices, N25Q064A.

The Total Phase socket boards I use provide about 3V for VCC, even when I select a 1.8V part type. Otherwise, this seems to program correctly. When I attach the Cheetah SPI Host Adapter to my custom socket board (where the flash device is powered by 1.8V), I cannot program the flash device. However, I can program it from my micro controller. I have isolated the flash part from the micro controller and I still cannot program the device at 1.8V with the Cheetah host adapter. What should I be doing?

Also, I tried running signals as slowly as the Flash Center allows, and I checked that all signals go to their correct places. What is see on the scope shows there may be a timing issue - I need to add a delay. How can I adjust the timing?

Thanks for your questions! The Cheetah SPI Host Adapter operates at 3.3V signal levels. The Total Phase SPI Flash Socket Boards (SOIC-8 and SOIC-16) support memory parts with SPI 3.3V logic level voltage. The Total Phase SPI socket boards cannot be configured to a lower logic level voltage (such as 1.8V). It is possible that the boards work in your system due to voltage margins. There may be also be some voltage margin in the 1.8V N25Q064 memory part. In addition, the two board designs are not identical. There may be some differences between the board design of your custom board and the Total Phase socket board.

To communicate with devices that operate at a lower voltage (such as the 1.8V device on your custom board), we recommend using a Level Shifter Board between the Cheetah host adapter and the target device. This setup will provide the correct SPI signals level to both devices.

Some of the Cheetah SPI timing parameters can be configured when using the appropriate software.

  • When using the Flash CenterTM Software (and its XML file), you cannot change the Cheetah timing parameters.
  • When using the Cheetah Software API, you can also configure the Cheetah timing parameters. For additional information about the Cheetah API, please refer to section 5 of the Cheetah Host Adapter User Manual.
  • When using the Cheetah GUI Software, you can change the delay parameter in the Cheetah GUI window, as shown below.

 

How to add a signal delay when using the Cheetah GUI. Figure 1: Cheetah SPI Host Adapter GUI Window

 

For additional information about the Cheetah SPI parameters please refer to section 2.5 of the Cheetah Host Adapter User Manual.

 

A timing diagram of the SPI Host Adapter SPI Signaling Characteristics. Figure 2: Cheetah SPI Host Adapter Parameters

 

 Table 1: Cheetah SPI Timing Parameters

Symbol Parameter

Min

Max

Units

clk Clock period

25

10000

ns

e Output Enable to SS control delay

8

8

clk

sac SS# assertion to first clock edge

6.5

7

clk

csd SS# deassertion from last clock edge

1.5

2

clk

op MOSI propagation time

0

5.8

ns

oh MOSI hold time

0.5

0.5

clk

is MISO setup time

4.8

N/A

ns

ih MISO hold time

0

N/A

ns

ud User Insertable Delay

8

232

tclk

 

For additional information about the Cheetah adapter and the accessory boards, please refer to the following documents:

Cheetah SPI Host Adapter Quick Start Guide
Cheetah Host Adapter User Manual
Cheetah GUI Software User Manual
Flash Center Software User Manual
Flash Socket Board User Manual
Total Phase Products
Product Selector Guide

We hope this answers your question. If you have other questions about our host adapters or other Total Phase products, feel free to email us at sales@totalphase.com or submit a request for technical support.

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