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Terminology and tips
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USB FX2 microcontroller stall term/definition is used to describe the situation where your TE USB FX2 module's FPGA works normally (you are still able to connect to FPGA using JTAG connection) but you are unable to connect to it via USB connection despite having the correct USB drivers installed. TE USB FX2 modules are industrial products and if wrong firmware is written in EEPROM (=> USB unresponsive but FPGA's working) it can easily corrected (without using JTAG connection) with EEPROM switch and USB connection: the solution is quite easy and fast (5-10 seconds) under Windows (implicit two-step recovery boot) and it is also possible under Linux (explicit two-step recovery boot). |
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Writing wrong (or corrupted) firmware to EEPROM will bring the USB FX2 microcontroller to stall. To bring it back out of a stall, the firmware recovery procedure differs upon the host operating system:
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Recovery Boot
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To default, the FX2 hardware (i.e with EEPROM isolated =>hardware's first stage loader) enumerates the USB FX2 microcontroller chip as VID=0x04B4 (Cypress) and PID=0x8613 (FX2LP), and provides support for loading firmware into RAM. To default, using the FX2 hardware (i.e with EEPROM isolated => hardware's first stage loader ) it is possible to write a new firmware in RAM but not in EEPROM. |
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Configurations that put firmware into external memory thus need a second stage loader. For typical "flat" memory architectures, a loader supporting the 0xA3 vendor request is used to write into that memory. Similarly, a second stage loader that supports the 0xA2 or 0xA9 vendor request is needed when writing boot firmware into an I2C EEPROM. These 0xA2, 0xA9 and 0xA3 vendor commands are conventions defined by Cypress.
(Implicit Two-Step) Recovery boot ≈ (Explicit Two-Step) Recovery Boot
It is possible to write in EEPROM only using a 2nd stage loader firmware supporting EEPROM programming (aka intermediate good firmware) running in RAM; normally the bootloader Vend_Ax.hex is used.
- In the case of (implicit two-step) recovery boot (at this time, only Windows) the 2nd stage (boot)loader firmware is loaded without the explicit intervention of the user.
- In the case of (explicit two-step) recovery boot (mainly Linux) the 2nd stage (boot)loader firmware is loaded with the explicit intervention of the user.
Both recovery boots use exactly the same procedure (under the hood, they are one and the same), but in Windows OS case the 2nd stage (boot)loader firmware step is hidden/implicit in loadEEPROM() function used by CyConsole, CyControl and OpenFutNet.
(Implicit Two-Step) Recovery Boot
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The 2nd stage loader firmware is loaded automatically without the explicit intervention of the user. At this time, it is only possible with Windows OS |
In an implicit two-step recovery boot (see here) the user should (the necessary device driver is assumed already installed)
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| The CyConsole's "S EEPROM" button is used to program 256-byte EEPROMs. When this button is clicked, the user is prompted to select a (.iic) file to load into the EEPROM. This button first downloads the Vend_Ax(_Fx2).bix file, then sends the 0xA2 vendor request to program the EEPROM. This button should not be used. |
(Explicit Two-Step) Recovery Boot
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| Explicit two-step recovery boot could be carried out with both Windows and Linux OSes. |
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Overview
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