Ruffian Heng embedded: startup of NXP i.MX rtxxx Series MCU (6. B) – complete flexspi nor connection mode (RT500)

Time:2021-7-30

Hello, I’m ruffian Heng, a serious technical ruffian. What ruffian Heng introduced to you today isFlexspi nor start connection mode of NXP i.MX RT500

In this series of articles on i.mxrt flexspi nor startup connection mode, ruffian Heng wrote four articles a year ago, including all i.mxrt models (rt600 / 1010 / 1015 / 1020 / 1050 / 1060 / 1064) that were available at that time. In recent years, i.mxrt series has added two new models, i.mxrt500, the second player belonging to i.mxrtxxx camp, and i.mxrt1170, the first generation God of war belonging to i.mxrt1xxx camp. Therefore, ruffian Heng will continue to be more literate.

Ruffian Heng wants to introduce the flexspi nor startup connection mode of i.mxrt500 today. You’d better put it before reading this articleFlexspi nor startup connection mode (rt600)After reading it first, I have a basic understanding of i.mxrtxxx series. We know that i.mxrt500 is an ultra-low power MCU based on arm cortex-m33 core, mainly for the intelligent wearable market. Like i.mxrt600, there is no internal nonvolatile memory. Connecting serial nor flash through flexspi interface is the preferred starting device.

i. There are two dual channel 8bit flexspi modules inside the mxrt500, which is enhanced compared with the i.mxrt600 single flexspi module. However, the two flexspi modules do not lead out port B on the chip I / O, and only one port (i.e. port a) can be used, so it is easier to start the connection mode. In addition, flexspi0 is mainly designed to connect flash (only otfad is connected inside the chip to realize online decryption), while flexspi1 is designed to connect hyperram / PSRAM to expand the buffer space of graphic display. OK, less gossip, let’s enter the text:

1、 Flexspi connection mode

The flexspi module IP itself supports two connection modes: individual mode: multiple flash time-sharing multiplexing flexspi, and only one flash is operated at the same time; Parallel mode: two flash can be operated together at the same time, and flexspi will automatically merge / split data (read / program). However, there is no port B support on i.mxrt500, so in fact, individual mode is the only choice.

2、 Flexspi pin involved

i. Mxrt500 provides two packages (wlcsp141 and fowlp249), and there are 9 models according to whether DSP and GPU are selected. The flexspi nor startup connection mode described below is not necessarily applicable to all packages (mainly wlcsp141 connection mode is less).

We can find the flexspi nor pin specified by bootrom in the non secure boot ROM chapter of the i.mxrt500 chip reference manual. Yes, only flexspi0 pin is used for flash boot device connection:

3、 Single flash connection mode (2 kinds)

The first way to connect flash is to connect four wire QSPI flash with six signal wires in flexspi0 port:

The second flash connection method is to use all 12 signal lines in flexspi0 port to connect eight wire octal flash (hyper flash is OK).

4、 Flash + PSRAM connection mode

i. Mxrt500-evk gives an example of Flash + PSRAM connection, that is, flexspi0 connects four wire / eight wire flash and flexspi1 connects PSRAM, which is also in line with the original intention of chip design. Of course, flexspi0 can also be connected to PSRAM, because i.mxrt500 can be started from the udhc interface (the code is stored in SD / EMMC).

Appendix. Pin definitions related to flexspi under fowlp249 package

So far, the connection mode of flexspi nor startup of NXP i.MX RT500 has been introduced by ruffian Heng. Where is the applause~~~

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