mc68hc908gr16 Freescale Semiconductor, Inc, mc68hc908gr16 Datasheet - Page 176

• Manufacturer Part Number: mc68hc908gr16
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Enhanced Serial Communications Interface (ESCI) Module
14.9.4 Arbitration Mode
If AM[1:0] is set to 10, the arbiter module operates in arbitration mode. On every rising edge of SCI_TxD
(output of the ESCI module, internal chip signal), the counter is started. When the counter reaches $38
(ACLK = 0) or $08 (ACLK = 1), RxD is statically sensed. If in this case, RxD is sensed low (for example,
another bus is driving the bus dominant) ALOST is set. As long as ALOST is set, the TxD pin is forced
to 1, resulting in a seized transmission.
If SCI_TxD is sensed 0 without having sensed a 0 before on RxD, the counter will be reset, arbitration
operation will be restarted after the next rising edge of SCI_TxD.
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RXD
RXD
RXD
Figure 14-22. Bit Time Measurement with ACLK = 1, Scenario A
Figure 14-23. Bit Time Measurement with ACLK = 1, Scenario B
Figure 14-21. Bit Time Measurement with ACLK = 0
MC68HC908GR16 Data Sheet, Rev. 5.0
MEASURED TIME
MEASURED TIME
MEASURED TIME
Freescale Semiconductor