C8051F320DK Silicon Laboratories Inc, C8051F320DK Datasheet - Page 117

• Manufacturer Part Number: C8051F320DK
• Description: DEV KIT FOR C8051F320/F321
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F320DK

• Contents: Evaluation Board, Power Supply, USB Cables, Adapter and Documentation
• Processor To Be Evaluated: C8051F320/F321
• Interface Type: USB
• Silicon Manufacturer: Silicon Labs
• Core Architecture: 8051
• Silicon Core Number: C8051F320
• Silicon Family Name: C8051F32x
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Silicon Laboratories C8051F320, C8051F321
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1260

On C8051F320/1 devices, OSCICL is factory calibrated to obtain a 12 MHz base frequency (f
tion 13.1.1 details oscillator programming for C8051F320/1 devices. Electrical specifications for the preci-
sion internal oscillator are given in Table 13.3 on page 125. Note that the system clock may be derived
from the programmed internal oscillator divided by 1, 2, 4, or 8, as defined by the IFCN bits in register
OSCICN. The divide value defaults to 8 following a reset.
13.1.1. Programming the Internal Oscillator on C8051F320/1 Devices
The OSCICL reset value is factory calibrated to result in a 12 MHz internal oscillator with a ±1.5% accu-
racy; this frequency is suitable for use as the USB clock (see Section 13.4). Software may modify the fre-
quency of the internal oscillator as described below.
Important Note: Once the internal oscillator frequency has been modified, the internal oscillator may not
be used as the USB clock as described in Section 13.4. The internal oscillator frequency will reset to its
original factory-calibrated frequency following any device reset, at which point the oscillator is suitable for
use as the USB clock.
Software should read and adjust the value of OSCICL according to Equation 13.1 to obtain the desired fre-
quency. The example below shows how to obtain an 11.6 MHz internal oscillator frequency.
f
f
The required change in period (T
Using Equation 13.1 and the above calculations, find OSCICL:
OSCICL is rounded to the nearest integer (14) and added to the reset value of register OSCICL.
T
BASE
DES
OSCICL
f
T
2.87 10
BASE
BASE
DES
is the desired internal oscillator frequency; T
Equation 13.1. Typical Change in Internal Oscillator Period with OSCICL
is the internal oscillator reset frequency; T

=
=
=
12000000Hz
----------------------- - s
12000000
9 –
----------------------- -
11600000
=
=
1
13.79
1
0.0025
–

----------------------- -
12000000
------------ -
f
BASE
1
1
T 0.0025
DES


OSCICL
) is the difference between the base period and the desired period.
=
2.87


BASE
Rev. 1.4
DES
10
------------ -
f
T
f
BASE
DES
DES
1
9 –
is the reset oscillator period.
is the desired oscillator period.
s

=
=
OSCICL
11600000Hz
----------------------- - s
11600000
1
C8051F320/1
BASE
). Sec-
117