and connect the USB lead.
The Red LED will light up indicating the USB-ISS is in boot-loader mode.
USB-ISS Multifunction USB Communications Module
Boot Mode Specification
USB-ISS Boot Mode
The USB-ISS Multifunction USB Communications Module has a built in boot loader. This means the firmware may be updated by the user when a new version becomes available. The boot-loader is based on the USB boot-loader provided by Microchip as part of their "Microchip Application Libraries" and can be downloaded from here.
You may run this program now.
| Now place a link on the USB-ISS Boot-loader pins as shown on the right and connect the USB lead. The Red LED will light up indicating the USB-ISS is in boot-loader mode. |
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You should see the following on the boot-loader:
If not, check the 2-pin link on your USB-ISS is in the boot position as indicated above and the USB cable is firmly connected.
Now Download the required USB-ISS firmware version from the list below:
| USB-ISS Firmware Version 2 | October 2010 | This is the first released version of the firmware (version 1 was internal testing only). |
| USB-ISS Firmware Version 3 | December 2010 | Fixed very short Led flash during Comms. It is now a fixed 43mS flash and much more visible. Fixed random returned bytes in I2C mode when nothing connected. It now returns 0xFF's in the buffer as the original USB-I2C module did. |
| USB-ISS Firmware Version 4 | April 2012 | Added workaround for PIC18F14K50 errata, Doc-F #2, which caused SPI crash in commands 0x92 and 0x93 when used with slow SCK frequencies. |
| USB-ISS Firmware Version 5 | April 2013 | Added I2C_TEST command to check for the existence of an I2C device. |
| USB-ISS Firmware Version 6 | July 2013 | Bugfix. Transmitting one byte in Serial Mode actually sent the full 32 byte buffer. |
| USB-ISS Firmware Version 7 | September 2015 | Bugfix. On power up, I/O's 1&2 are in unknown state (high or low or input). They now power up to input mode |
| USB-ISS Firmware Version 8 | February 2016 | Bugfix. If write failed (NACK received) while using the I2C_DIRECT command, bus was held open. |
| USB-ISS Firmware Version 9 | July 2020 | Added support for clock stretching of acknowledge bit within the software I2C implementation |
Click on "Open Hex File" and load in the new version, then press "Program/Verify". You should see the following:
That's it!
To run your new version you should remove the boot-loader link from the USB-ISS module and click the "Reset Device" button.
The Green Led will light up indicating normal operation.