Download HC12compact V1.0 User Manual

HC12compact
9. Peripherals on the System Bus
The HC812A4 provides several Chip Select signals. The signals
/CS0../CS3 (Port F) are used on the HC12compact to control peripheral
devices on the system bus:
Signal
Address Function
/CS0
$0200
CAN-Controller (Read-/Write-Access to the selected Register/Address)
/CS1
$0300
CAN-Controller (select Register/Address)
/CS2
$0380
LC-Display (alphanum.) control or general
purpose select signal (associated with R/W and
E-Clock)
/CS3
$0280
general purpose Chip Select
Overview Chip Select Signals
Normally the initialization code of the microcontroller application
should stretch the chip select signals (up to 3 E-Clocks). In this way the
MCU can communicate also with slow peripheral devices. The
maximum cycle time is 1µs at a 16 MHz xtal clock.
CAN-Controller
The CAN (Controller Area Network) is a multimaster network
protocol, which originally started in the the automotive industry. Now it
has become an industry standard, supported by a large number of
manufacturers.
Motorola supports the CAN standard too, e.g. with the On-Chip
CAN module of the HC912BC32. Since the HC812A4 does not have a
CAN module On-Chip, the HC12compact provides an external CAN
controller chip.
The device used is a SJA1000 by Philips (compatible to the former
PCA82C200). It contains a complete implementation of the lower level
layers of the CAN protocol. This means, the user need not to deal with
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