Recent content by tigercat

The 74LCX126 is for level shifting, because Teensy3 is 5V, the memory chips are not. It's not needed for Teensy4. I am building a memory expansion board that's shorter so it fits on Teensy 4.0 footprint (also 4.1 of course) and has (6) 23LC1024 chips. It uses the same memory addressing scheme...

Thank you RedoX! Your TsyEraseALL works great (from the GUI too) and is a good workaround for reconfiguring the EEPROM. It will come in very handy for Teensy 3.1 experimentation. Here is another piece (see attachment), it's a utility program to view & set the EEPROM configuration. It shows...

Yes, they should state that once you set the EEPROM it can't be changed. And the bootloader should have been designed so that it bulk erases the K20 when you hold down the button for 30 seconds. That would have made the Teensy board unbrickable, plus it would have allowed for easy...

The Teensy EEPROM works fine; the problem is that there is no published way to change the Teensy EEPROM configuration once it's been set. For production that's fine, but for experimentation and development it'd be nice to be able to reconfig the FlexRam/FlexNVM to different settings. So far...

Detailed Unbrick Procedure Here's a detailed Teensy ERASE_ALL unbrick procedure using a J-Link EDU, with thanks to froeber for all the technical hints that were needed to figure this out... Jumper the MINI54 reset signal to ground, which keeps it from interfering with the MK20 while we...

Thanks Fred, that fills in some of the pieces of this puzzle. Also AN4386 (http://cache.freescale.com/files/microcontrollers/doc/app_note/AN4835.pdf?fasp=1&WT_TYPE=Application%20Notes&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation&fileExt=.pdf) explains the issues in good detail...

Yes, the SWD traces can be jumpered in and the board eventually restored, but that's another project. As an Arduino type part this is a fail because there is no easy recovery available, so as the Teensy software developer recommends I'm just going to buy some spare Teensy 3.1 boards and not...

Good idea, but the SWD pins are connected to the MINI54 controller chip, which loads the USB bootloader into the MK20. Apparently there are hardware config parameters in the middle of the MK20 flash, including an important mystery value at 0x41C, that get wiped out by an Erase All Blocks...

Don't try this at home, and by the way how do you unbrick a Teensy 3.1? Yep, froeber is right. And now I've got myself a bricked Teensy 3.1. It sounded like froeber said simply do a ERASE_ALL_BLOCKS like this... uint16_t do_flash_cmd[] = { 0xf06f, 0x037f, 0x7003, 0x7803, 0xf013, 0x0f80...

The V1.20 Teensyduino 9-bit serial support incorrectly implements 9-bit receive, resulting in the 9'th bit being randomly dropped. This is because, per the datasheet, the UART_C3 register must be read before UART_D for it to be valid. So the order of these lines of code in serial1.c...