SAF82525 Infineon Technologies AG, SAF82525 Datasheet - Page 46

• Manufacturer Part Number: SAF82525
• Description: Data Communications ICs
• Manufacturer: Infineon Technologies AG

The circuit mentioned above results in a slower data transfer with the HSCX. HSCX usually
performs block transfers. The block length is up to 32 bytes. The DMA request line of the IC
remains active as long as more data are needed. Having transmitted the last byte the DMA
request is being reset. Using the additional circuit the DMA request line will be active at least
shortly before T4. So the next DMA cycle will be started four (instead of two) clock cycles later.
Therefore the maximum transmission rate is reduced from 1.25 Mbyte/s to 1.04 Mbyte/s (clock
rate: 12.5 MHz).
For more information refer to chapter 7.2 (Data Transmission: DMA Mode), chapter 7.3 (Data
Reception: DMA mode), and Appendix C (Application Example HSCX with 80(C)188 using
DMA).
Semiconductor Group
CLOCKOUT
DRQTx
DRQ
RD
(Memory)
CS
(FIFO)
WR
(FIFO)
t
f
12.5
16
8 MHz
DRHSYS max
CLKOUT
MHz
MHz
= T2 + T3
t
125 ns
62.5
80
CLCL
ns
ns
+
T4/2
- t
T1
t
CVCTV
56 ns
47
31
CVCTV
ns
ns
+ t
T2
CHCSX
t
CHCSX
5 ns
5
5
T3
ns
ns
t
CLCSV
T4
46
t
DRHSYS max
158
130
261ns
T1
ns
ns
T2
t
CVCTV
t
DRHSYS
T3
t
CHCSX
T4
ITD02700
SAB 82525
SAB 82526
SAF 82525
SAF 82526