P4 and the 16045148

[Ludis Langens]

Pat Ford wrote:
> 
>  Ludis is it possible the 45148 is a variant of the 68hc24 port replacement unit?
> the pin out is off and pin count is funky but it seems to fit in with some of the
> 'hc11 eval boards schematics

Nope.  It appears to be similar the TPU (Time Processing Unit) found in
a 68332.  It has lots of built in smarts.  The 45148 is an update of the
23263 chip used in C3 ECMs.  The register map is similar.  One portion
whose functionality is the same is the PWM outputs.  The 23263 has
three, the 45148 has more.  Both chips use the same control word for
each PWM channel.  It is:

ratePWM128	EQU	%1111000000000000	;128 Hz rate, 8 bit width
ratePWM64	EQU	%1110000000000000	;64 Hz rate, 9 bit width
ratePWM32	EQU	%1101000000000000	;32 Hz rate, 10 bit width
ratePWM16	EQU	%1011000000000000	;16 Hz rate, 11 bit width
ratePWM8	EQU	%0111000000000000	;8 Hz rate, 12 bit width

The pulse width field is right justified in the low 12 bits.


It appears that some P4 ECMs have three of these TPU modules.  In
addition to one at the usual 0x3fc0-0x3ffd, there is one at
0x3f80-0x3fbd, and another at 0x3dc0-0x3dfd.  The highest address (ie
0x3ffc) is a control word for the entire timer module.

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/