DEMO9S08EL32AUTO Freescale Semiconductor, DEMO9S08EL32AUTO Datasheet - Page 312

• Manufacturer Part Number: DEMO9S08EL32AUTO
• Description: DEMO BOARD EL32 AUTO
• Manufacturer: Freescale Semiconductor
• Type: MCUr

Specifications of DEMO9S08EL32AUTO

• Contents: Board, Cable, CD and Documentation
• Processor To Be Evaluated: MC9S08EL32
• Data Bus Width: 8 bit
• Interface Type: RS-232, USB
• Operating Supply Voltage: 12 V
• For Use With/related Products: MC9S08EL32
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Development Support
Figure 17-4
shows the host receiving a logic 1 from the target HCS08 MCU. Because the host is
asynchronous to the target MCU, there is a 0-to-1 cycle delay from the host-generated falling edge on
BKGD to the perceived start of the bit time in the target MCU. The host holds the BKGD pin low long
enough for the target to recognize it (at least two target BDC cycles). The host must release the low drive
before the target MCU drives a brief active-high speedup pulse seven cycles after the perceived start of the
bit time. The host should sample the bit level about 10 cycles after it started the bit time.
BDC CLOCK
(TARGET MCU)
HOST DRIVE
HIGH-IMPEDANCE
TO BKGD PIN
TARGET MCU
SPEEDUP PULSE
HIGH-IMPEDANCE
HIGH-IMPEDANCE
PERCEIVED START
OF BIT TIME
R-C RISE
BKGD PIN
10 CYCLES
EARLIEST START
OF NEXT BIT
10 CYCLES
HOST SAMPLES BKGD PIN
Figure 17-4. BDC Target-to-Host Serial Bit Timing (Logic 1)
MC9S08EL32 Series and MC9S08SL16 Series Data Sheet, Rev. 3
314
Freescale Semiconductor