Under factory default (OTP_BOOTPIN_CONFIG_KEY != 0x5A) and no emulator connected, MCU checks below two pins at reset to determine the booting mode.
|
MODE |
GPIO24 | GPIO32 |
Boot mode |
| Mode 0 | 0 | 0 | Parallel I/O |
| Mode 1 | 0 | 1 | SCI / Wait (RAM boot) |
| Mode 2 | 1 | 0 | CAN |
| Mode 3 | 1 | 1 | Flash (USB) |
easyDSP uses two kinds boot mode, SCI boot
mode for RAM booting, Flash boot mode for flash rom booting.
Therefore, below connection is recommended between easyDSP
and MCU.
- Factory default
setting is assumed
- power pin (#4) of
easyDSP 5x2 header should be connected to 3.3V
- SCIA_RX = GPIO28, SCIA_TX = GPIO29
- In case there
is a reset IC between easyDSP /RESET and MCU /XRS, it should transfer easyDSP
/RESET signal to MCU /XRS within 0.5sec
- TX/RX pins are directly connected to
MCU pins
- In case you
insert buffer IC between easyDSP header and MCU, place buffer IC directly
to easyDSP header so that all resistors can be connected to directly MCU
- /BOOT pin is connected to GPIO24 via 2kΩ series resistor
- /RESET pin is connected to reset generation
circuit of MCU
board (Time duration of /RESET pin is around 500msec)
- In case you use pull-up resistor to each pin, the value
of pull-up resistor should be higher than a few kilo ohm since there is 100Ω series resistor inside easyDSP
pod
Please be careful when you use
your own pull-up or pull-down resistor on the easyDSP signal pins. Please use
appropriate filter circuit to your reset generation circuit to prevent
unintentional reset generation.