Hardware manual

Microcomputer Technical Q&A
93
Q&A No.: QAH8S-219
Category: TPU
Subject: Cascaded Connection
Question
Can cascaded connection be used with the TPU?
Answer
Yes. The two timer register combinations shown below can be used. The upper and lower registers
operate in synchronization with the clock.
1. TCNT1 + TCNT2
2. TCNT4 + TCNT5
With combination 2, the following points must be noted.
• Longword access cannot be used on the TCNT4/TCNT5 (TCNT, TGR) register pair, so two
word accesses must be used. Consequently, there will be a lag between the read/write timings
of the upper and lower registers.
• Compare matches occur separately for the upper and lower registers. In the case of an upper
register compare match, in particular, care is required if the lower counter overflows or
underflows.
Note: TCTN4 and TCNT5 are not provided in the H8S/2245 Series.
Applicable Products
Applicability Series Applicability Series Applicability Series
Entire H8S Series Yes H8S/2655 Yes H8S/2350
Yes H8S/2355 Yes H8S/2357 Yes H8S/2345
Yes H8S/2245 H8S/2148 H8S/2144
H8S/2138 H8S/2134 H8S/2128
H8S/2124 — — — —