Chapter 10: Programmable Timer/Contents
TX7901 User’s Manual (Rev. 6.30T – Nov, 2001)
10-1
10. Programmable Timer/Counters
10.1 Features
The TX7901 Programmable Timer/Counters consist of three timer “channels”, Timer 0,
Timer 1, and Timer 2. Timer 0 operates only in the Interval Timer Mode. Timer 1 is capable
of operating only in the Interval Timer and Pulse Generation Modes. Timer 2 is capable of
operating in the Interval Timer, Pulse Generator, and Watchdog Timer Modes. All three
modes of operation utilize a 24-bit up counter. There is one counter per timer channel. The
three counter modes operate as described below.
10.1.1 Interval
Timer
Mode
In this mode, the timer generates periodic interrupts and can be configured to use internal or
external clock inputs to trigger the counter. The external clock input can be configured to
trigger the counter on its rising or falling edge.
10.1.2 Pulse
Generator
Mode
In this mode, the Timer output can be configured to provide waveforms of specific frequency
and duty ratio.
10.1.3 Watchdog Timer Mode
In this mode, the timer monitors and times out system runaway conditions.
10.1.4 Internal or External Clock Division
The internal or external clock source selected for a particular counter may be individually
scaled down to 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, or 1/256 of its input frequency.
Note:
When using an external clock, its frequency should be less than or equal to one half that of the internal G-
Bus clock (i.e. less than or equal to 33/25 MHz).
Table 10-1 Timer Modes and Channels
Channel
Mode
Description
0
1
2
Interval Timer
Periodic interrupt
9
9
9
Pulse Generator
Provides waveform of specified frequency and
duty rate.
9
9
Watchdog Timer
Detects runaway condition. Causes NMI or
sysReset.
9
Summary of Contents for TMPR7901
Page 1: ...TX System RISC TX79 Family TMPR7901 Symmetric 2 way superscalar 64 bit CPU ...
Page 14: ...Handling Precautions ...
Page 15: ......
Page 17: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 41: ...4 Precautions and Usage Considerations 4 2 ...
Page 42: ...TX7901 User s Manual Rev 6 30T November 2001 DOCUMENT NUMBER M 99 00004 07 ...
Page 43: ......
Page 259: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 1 13 Removed ...
Page 260: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 2 ...