PKP
VS1000 P
ROGRAMMER
’
S
G
UIDE
VSMPG
The divide-by-2 and divide-by-256 blocks can be active at the same time, resulting in a
master clock that is divided by 512. With the standard 12 MHz crystal, this results in a
system clock of just above 23 kHz (23437.5 Hz).
12.4
I/O Pin Routing
The System Controller controls the I/O pins of the device, routing signals to/from the
peripherals such as a serial port or GPIO controller.
GPIOn_MODE Bits
Name
Bits
Description
periph/gpioX
15:0
bit vector; 1=peripheral 0=GPIO
GPIO0_MODE and GPIO1_MODE control output signal routing for the I/O pins. Most
pins are multiplexed between general purpose input/output and a peripheral function.
Pins are controlled by peripheral functions by default. Writing “0” to a bit in GPIOn_MODE
enables direct control over the pin.
Regardless of GPIOn_MODE register value, the input data (1/0 state of pin) can always
be read from the GPIOn_IDATA register (See section: Interruptable General Purpose
IO).
Switching a pin to GPIO mode can be used to disable data flow from a pin to a peripheral
function. The following peripheral input signal values are set when the corresponding
pin is in GPIO mode:
Peripheral Function Input Signal Values When pin is in GPIO Mode
GPIO
Function
Value
GPIO0[7:0]
Nand Flash data input
00000000
GPIO0[8]
Nand Flash Ready
1
GPIO1[0]
SPI Slave Select
1
GPIO1[1]
SPI Clock
1
GPIO1[2]
SPI MISO
1
GPIO1[3]
SPI MOSI
1
GPIO1[5]
UART Receive
1
12.5
VS1000 ROM code usage
The ROM code in VS1000 has the following usage for the System Controller:
At boot-up time, if pin D7 (pin number 12 in LQFP package) is pulled high, the ROM
software raises IOVDD from 1.8V to 3.3V. If it is pulled low, IOVDD remains at 1.8V. The
pin should not be left floating.
The default core voltage has been raised to 2.2V in VS1000B.
The ROM code expects a 12.000 MHz crystal input.
Rev. 0.20
2011-10-04
Page