mc68hc05x4dw Freescale Semiconductor, Inc, mc68hc05x4dw Datasheet - Page 16

• Manufacturer Part Number: mc68hc05x4dw
• Description: Xc68hc705x4 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Bootloader data
format
Modes of Operation and Pin Descriptions
MC68HC05X4 Rev 1.0
Serial data byte format is 8 data bits, no parity, one stop bit. The baud
rate for both transmission and reception will be 9600 for a bus frequency
(f
Serial data packet format is:
Program execution will automatically commence after the last byte is
received.
Port A pins are used as follows:
PA0
PA1
PA2
outputs the contents of the user ROM to port B one byte at a time.
PA3
first byte received is the total byte count (COUNT) for the message. The
serial bytes received are loaded, starting at RAMST + 1. When all the
bytes have been downloaded the program will automatically begin
executing from RAMST + 1. The program will sit in a Wait loop
indefinitely if fewer than ‘COUNT’ bytes are received.
This can be used to allow Port A to be tested (using a user generated
routine) as follows:
ensuring that ‘COUNT’ is greater than the number of bytes to be
transferred. Now, while the MCU is waiting for further bytes to arrive, apply
a reset signal. Whilst holding RESET low, connect port A as required for
testing, then release RESET. The test program in RAM will now test port A.
PA4
should be reset if this happens.
OP
Freescale Semiconductor, Inc.
) of 2MHz.
For More Information On This Product,
‘High’
‘Low’
‘High’
‘Low’
‘High’
‘Low’
Modes of Operation and Pin Descriptions
Go to: www.freescale.com
(count) (byte 0) (byte 1) . . . (byte (count – 2))
Serial receive data (RXD) – 9600 baud at fOP = 2MHz
Serial transmit data (TXD) – 9600 baud at fOP = 2MHz
Program enters load/execute mode.
Bootloader program runs a simple test routine which
(This bit is read only if PA2 is ‘High’.)
Load – bootloader routine waits for a serial byte. The
Execute – The program passes control to RAMST +1.
Download program into RAM with PA3 = ‘High’, but
This indicates normal operation.
This bit is cleared if an overrun error occurs. The device
4-modes