Datasheet

VS1053b Datasheet
7 SPI BUSES
7.4.2 SCI Write
0 1 2 3 4 5 6 7 8 9 10 11 12 13 30 3114 15 16 17
0 0 0 0 0 0 1 0 0 0 0
3 2 1 0
1 0
X
address
XCS
SCK
SI
15 14
data out
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0SO
0 0 0 0
X
0
instruction (write)
DREQ
execution
Figure 10: SCI word write
VS1053b registers are written from using the following sequence, as shown in Figure 10. First,
XCS line is pulled low to select the device. Then the WRITE opcode (0x2) is transmitted via the
SI line followed by an 8-bit word address.
After the word has been shifted in and the last clock has been sent, XCS should be pulled high
to end the WRITE sequence.
After the last bit has been sent, DREQ is driven low for the duration of the register update,
marked “execution” in the figure. The time varies depending on the register and its contents
(see table in Chapter 9.6 for details). If the maximum time is longer than what it takes from the
microcontroller to feed the next SCI command or SDI byte, status of DREQ must be checked
before finishing the next SCI/SDI operation.
7.4.3 SCI Multiple Write
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
0 0 0 0 0 0 1 0 0 0 0
3 2 1 0
address
XCS
SCK
SI
15 14
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0SO 0 0
0
instruction (write)
DREQ
1 0
X
0 0
X
execution
1
0 15 14
data out 1
data out 2
0 0 0 0
execution
X
31
30
32 3329
d.out n
m−2m−1
Figure 11: SCI multiple word write
VS1053b allows for the user to send multiple words to the same SCI register, which allows
fast SCI uploads, shown in Figure 11. The main difference to a single write is that instead of
Version: 1.22, 2014-12-19 21