Serial Bus Commands - Texas Instruments SimpleLink CC2620 Technical Reference Manual

Bootloader Interfaces
8.2.2.2 SSI Transport
The connections required to use the SSI port are the following four pins:
• SSI0 TX
• SSI0 RX
• SSI0 Clk
• SSI0 Fss
The device communicating with the bootloader drives the SSI0 RX, SSI0 Clk, and SSI0 Fss pins, while the
CC26xx and CC13xx devices drive the SSI0 TX pin.
The format used for SSI communications is the Motorola format with SPH set to 1 and SPO set to 1 (see
Figure 20-9 for more information on this format). The SSI interface has a hardware requirement that limits
the maximum rate of the SSI clock to be at most 1/12 the frequency of the SSI module clock
(48 MHz / 12 = 4 MHz).
The master must take special consideration (regarding the use of the SSI0 interface) due to the
functionality of not configuring any output pins before the external master device has selected a serial
interface.
NOTE: On the first packet transferred by the master, no data is received from the bootloader while
the bootloader clocks out the bits in the first byte of the packet.
When the bootloader detects that 1 byte has been received on SSI0 RX, the bootloader
configures the SSI0 TX output pin.
Before transmitting the next byte in the first packet, the master must include a small delay to
ensure that the bootloader has completed the configuration of the SSI0 TX output pin.

8.2.3 Serial Bus Commands

Table 8-3 lists the commands supported by the custom protocol on the UART0 and SSI0 bootloader
interfaces.
Each command is transferred within a protocol packet. The first 2 bytes within a packet are the size byte
followed by the checksum byte. The third byte holds the command value that identifies the command; the
values for all the supported commands are listed in the Command Value column of
remaining bytes within the packet are command parameters. See
for a complete description of the command byte and parameter bytes for each command.
Command
COMMAND_PING
COMMAND_DOWNLOAD
COMMAND_GET_STATUS
678 Bootloader
Table 8-3. Supported Bootloader Commands
Command Value Bytes in Packet
0x20 3
0x21 11
0x23 3
Copyright © 2015, Texas Instruments Incorporated
Table
Section 8.2.3.1 through
Description
Receives an acknowledge from the bootloader
indicating that communication has been
established.
Prepares flash programming. Specifies from where
to program data in flash and how many bytes will
be sent by the COMMAND_SEND_DATA
commands that follow.
Returns the status of the last command that was
issued. Typically, this command must be received
by the bootloader after every command is sent to
ensure that the previous command was successful.
See Table 8-4 for defined status values. The status
is returned within a protocol packet of 3 bytes.
SWCU117C – February 2015 – Revised September 2015
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8-3. The
Section 8.2.3.12