Texas Instruments SimpleLink CC2620 Technical Reference Manual page 1478

RF Core HAL
When deciding in which memory area to place data, consider which modules may be powered down:
• The radio RAM is accessible for the radio CPU at any time, but does not have retention when the radio
is powered down. Data that must be retained must therefore be copied into or out of the radio RAM
whenever the radio is powered up or down, respectively.
• The system RAM has retention in most low-power modes. If the system side is powered down, the
radio CPU requests that it is powered up again to access the RAM. The active current consumption
from the radio CPU accessing the system RAM is higher than the current consumption from accessing
the radio RAM, especially if the system side could otherwise have been powered down.
• The flash always has retention, and can only store parameters that are not written by the radio CPU.
As with accessing the system RAM, the radio CPU must ensure that the system side is powered up to
access the flash. The power consumption from the radio CPU accessing the flash is higher than the
current consumption from accessing the system RAM, but in most cases the difference is negligible
due to few accesses.
• The lowest peak-power consumption is obtained by putting all data structures in the radio RAM and
powering down the system side while the radio CPU is running. In some cases the average power
consumption may be lower by putting data structures in the system RAM, as less copying is then
needed, and the system side can still be powered down for long periods (for instance, while the
receiver is in sync search).
A radio operation command causes the radio hardware to be accessed. Radio operation commands can
do operations such as transmitting or receiving a packet, setting up radio hardware registers, or doing
more complex, protocol-dependent operations. A radio operation command can normally be issued only
while the radio is idle.
An immediate command is a command to change or request status of the radio, or to manipulate TX or
RX data queues. An intermediate command can monitor status such as received signal strength. An
immediate command can be issued at any time, but the response is, in many cases, only of interest while
a radio operation is ongoing.
A direct command is an immediate command with no parameters, or in some cases, a direct command
has 1- or 2-byte parameters. A direct command is issued by sending a value to the CMDR register with
the format of Figure
command to run. Bits 8 through 15 may contain an optional parameter if specified for the command.
23.3.2.2 Command Status
After a command is issued, the CMDSTA register is updated by the radio CPU, causing an RFCMDACK
interrupt to be sent back to the system CPU. This update occurs after the command completes for
immediate and direct commands, and after the command is scheduled for radio operation commands. No
new command may be issued until this interrupt is received. The CMDSTA register consists of 32 bits; the
8 LSBs give the result, while the upper 24 bits may be used for specific signaling in each command.
Figure 23-5 shows this format.
return byte 3
31
msb
In the result byte, bit 7 indicates whether an error occurred or not. The result byte of 0x00, meaning
pending, is produced automatically by the radio doorbell hardware when a command is issued, and the
other bits in the CMDSTA register also become 0, which is the value of CMDSTA before the
RF_CMD_ACK interrupt is raised.
1478
Radio
23-4. The 16 most significant bits (MSBs) contain the command ID of the immediate
Figure 23-5. Format of CMDSTA Register
return byte 2
24
Copyright © 2015, Texas Instruments Incorporated
return byte 1
16
SWCU117C – February 2015 – Revised September 2015
www.ti.com
result
8
lsb
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