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KFDtool/doc/DEV_NOTES.md

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Developer Documentation

Hardware

Test Points

The PT100 PCB has 15 test points, numbered T1 to T15.

NOTE: T1, T2, T4, T5, T6, T7, T8, T9, T10, T11 are referenced to GND (T3). T4, T5, T6, T7, T8, T9, T10, T11 are 3.3V level signals.

NOTE: T12, T13, T15 are referenced to GNDISO (T14). T12, T13, T15 are 5V level signals.

  • T1 - 5V

    • USB 5V DC power rail
    • Used for MCU USB circuitry and digital isolator power supply

  • T2 - 3V3

    • Regulated 3.3V DC power rail
    • Used for MCU core/ports and EEPROM

  • T3 - GND

    • Ground for PC connected circuitry (MCU/EEPROM)

  • T4 - SBWTDIO

    • MCU debug/programming interface, connects to SBW RST on TI LaunchPad ez-FET header

  • T5 - SBWTCK

    • MCU debug/programming interface, connects to SBW TST on TI LaunchPad ez-FET header

  • T6 - GPIO1

    • General purpose I/O for debugging, pin P4.4 on MCU, hardware serial port on MCU (TX)
    • Currently outputs a LOW when interrupts are enabled, and outputs a HIGH when interrupts are disabled (during reception of byte during timer operation)

  • T7 - GPIO2

    • General purpose I/O for debugging, pin P4.5 on MCU, hardware serial port on MCU (RX)
    • Currently toggles state when the MCU_DATA_IN_3V3 signal is being sampled

  • T8 - MCU_DATA_OUT_3V3

    • Controls transistor for DATA signal
    • MCU_DATA_OUT_3V3 LOW = transistor off = DATA line pulled HIGH (5VISO) by pull up resistor
    • MCU_DATA_OUT_3V3 HIGH = transistor on = DATA line pulled LOW (GNDISO) by transistor

  • T9 - MCU_DATA_IN_3V3

    • Level shifted version of KFD_DATA_IN

  • T10 - MCU_SENSE_OUT_3V3

    • Controls transistor for SENSE signal
    • MCU_SENSE_OUT_3V3 LOW = transistor off = SENSE line pulled HIGH (5VISO) by pull up resistor
    • MCU_SENSE_OUT_3V3 HIGH = transistor on = SENSE line pulled LOW (GNDISO) by transistor

  • T11 - MCU_SENSE_IN_3V3

    • Level shifted version of KFD_SENSE_IN

  • T12 - KFD_DATA_IN

    • Target DATA signal

  • T13 - KFD_SENSE_IN

    • Target SENSE signal

  • T14 - GNDISO

    • Target isolated ground

  • T15 - 5VISO

    • Target isolated 5V DC power rail

External Logic Analyzer

A external logic analyzer can be connected to monitor the TWI signals independent of the KFDtool. The TWI physical protocol is close to a UART signal, and therefore UART protocol decoders of logic analyzers can be used.

There is no stop bit in the TWI protocol, where a stop bit is part of the UART protocol. The logic analyzer reports a framing error where it expects a stop bit, however this can be safely ignored.

The following screenshots are of the Saleae logic analyzer software.

  • Ground - connected to T3
  • Channel 00 "GPIO1" - connected to T6
  • Channel 01 "GPIO2" - connected to T7
  • Channel 02 "DATA_OUT" - connected to T8
  • Channel 03 "DATA_IN" - connected to T9
  • Channel 04 "SENSE_OUT" - connected to T10
  • Channel 05 "SENSE_IN" - connected to T11
  • Trigger - Channel 03 "DATA_IN" falling edge

image

Async serial (UART) analyzer settings:

image

Firmware

TODO

Software

TODO