Freescale Semiconductor MC68HC08KH12 Manuel d'utilisateur Page 187

  • Télécharger
  • Ajouter à mon manuel
  • Imprimer
  • Page
    / 262
  • Table des matières
  • MARQUE LIVRES
  • Noté. / 5. Basé sur avis des utilisateurs
Vue de la page 186
MC68HC(7)08KH12Rev. 1.1 Advance Information
Freescale Semiconductor
187
DDRA[7:0] — Data Direction Register A Bits
These read/write bits control port A data direction. Reset clears
DDRA[7:0], configuring all port A pins as inputs.
1 = Corresponding port A pin configured as output
0 = Corresponding port A pin configured as input
NOTE: Avoid glitches on port A pins by writing to the port A data register before
changing data direction register A bits from 0 to 1.
Figure 12-3 shows the port A I/O logic.
Figure 12-3. Port A I/O Circuit
When bit DDRAx is a logic one, reading address $0000 reads the PTAx
data latch. When bit DDRAx is a logic zero, reading address $0000
reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit. Table 12-2 summarizes
the operation of the port A pins.
Address: $0004
Bit 7654321Bit 0
Read:
DDRA7 DDRA6 DDRA5 DDRA4 DDRA3 DDRA2 DDRA1 DDRA0
Write:
Reset:00000000
Figure 12-2. Data Direction Register A (DDRA)
READ DDRA ($0004)
WRITE DDRA ($0004)
RESET
WRITE PTA ($0000)
READ PTA ($0000)
PTAx
DDRAx
PTAx
INTERNAL DATA BUS
Vue de la page 186
1 2 ... 182 183 184 185 186 187 188 189 190 191 192 ... 261 262

Commentaires sur ces manuels

Pas de commentaire