MRF49XA Datasheet, PDF (42/102 Pages) Microchip Technology – ISM Band Sub-GHz RF Transceiver

MRF49XA
REGISTER 2-16: BCSREG: BATTERY THRESHOLD DETECT AND CLOCK OUTPUT VALUE SET
REGISTER (POR: 0xC000)
R/W-1
bit 15
R/W-1
R/W-0
R/W-0
R/W-0
CCB<15:8>
R/W-0
R/W-0
R/W-0
bit 8
R/W-0
bit 7
R/W-0
COFSB<2:0>
R/W-0
R/W-0
r
R/W-0
R/W-0
R/W-0
LBDVB<3:0>
R/W-0
bit 0
Legend:
R = Readable bit
-n = Value at POR
r = reserved bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
bit 7-5
bit 4
bit 3-0
CCB<15:8>: Command Code bits
The command code bits (11000000b) are serially sent to the microcontroller to identify the bits to be
written in the BCSREG.
COFSB<2:0>: Clock Output Frequency Set bits
These bits set the output clock frequency which can be used to run an external host microcontroller.
111 = 10 MHz
110 = 5 MHz
101 = 3.33 MHz
100 = 2.5 MHz
011 = 2 MHz
010 = 1.66 MHz
001 = 1.25 MHz
000 = 1 MHz
Reserved: Write as ‘0’
LBDVB<3:0>: Low Battery Detect Value bits
These bits set the decimal value to calculate the battery detect threshold voltage level.^(1,2)
Note 1:
2:
When the battery level goes down by 50 mV below this value, the LBTD bit (STSREG<10>) is set, indicating
that the battery level is below the programmed threshold. This is useful in monitoring discharge-sensitive
batteries, such as Lithium cells. The low battery detect can be enabled by setting the LBDEN bit
(PMCREG<2>) and can be disabled by clearing the bit.
The low battery threshold value is programmable from 2.2V to 3.8V by using Equation 2-9.
EQUATION 2-9:
Threshold Voltage Value = 2.25 + 0.1 x (LBDVB<3:0>)
where:
LBDVB<3:0> is the Decimal Value from 0 to 15.
DS70590B-page 40
Preliminary
© 2009 Microchip Technology Inc.