TDMA Digital Radio Processor
CMX7161
7.4
Function Image™ Loading
The Function Image™ (FI) which defines the operational capabilities of the device may be obtained from
the CML Technical Portal, following registration and authorisation. This is a 'C' header file which contains
blocks of data to be included with the host controller software or programmed into an external serial
memory. The Function ImageTM size will never exceed 128 kbytes and a typical FI may be considerably
smaller than this. Note that the BOOTEN1/2 pins are only read at power-on, or when the RESETN pin
goes high, or following a C-BUS General Reset, and they must remain stable throughout the FI loading
process. After an FI load has completed the BOOTEN1/2 pins are ignored by the CMX7161 until the next
power-up or Reset.
The BOOTEN1/2 pins are both fitted with internal low current pull-up devices. For serial memory loading
BOOTEN2 should be pulled low by connecting it to DV either directly or via a 47k resistor (see Table 2).
ss
The boot loader reports back the checksum of each FI data block in the C-BUS Device Information - $4D,
read register. These can be read back in sequence and checked against the values provided along with
the FI to verify that it has loaded correctly. After the FI has finished loading the CMX7161 will also report its
product identification code ($7161) and version code in the Device Information Register.
Once the Function Image™ is loaded and the CMX7161 has fully initialised itself, the Mode bit in the
register is set and the device enters Sleep mode by default. The contents of the Device Information
Register are valid while the CMX7161 remains in this initial Sleep state but the register should NOT be
accessed after any active operating mode has been selected.
If the host detects a brownout, the FI must be reloaded. The BOOTEN1/2 pins should be configured
appropriately and a General Reset should then be issued or the RESETN pin used to reset the CMX7161.
The appropriate FI load procedure can then be followed.
Table 2 BOOTEN Pin States
BOOTEN2
BOOTEN1
C-BUS host load
reserved
Serial Memory load
reserved
1
1
0
0
1
0
1
0
7.4.1 FI Loading from Host Controller
The Function Image™ can be included with the host controller software for download into the CMX7161 at
power-up over the C-BUS interface. This is done by writing the FI data into the FI Load Register ($49
write) which supports streaming operation. The BOOTEN1/2 pins must first be set to the C-BUS load
configuration and the CMX7161 then powered up or Reset before the FI data is sent over C-BUS.
Depending on the rate of data transfer by the host, the FI data may be buffered by the device during
loading. The Transmit FIFO Level Register ($4B read) indicates the fill level of the FI load FIFO which has
a maximum capacity of 128 bytes. This level should be checked to ensure the buffer does not overflow.
Otherwise FI download time is limited only by the clock frequency of the C-BUS. With a 19.2MHz SCLK it
should take less than 250ms to complete even when loading the largest possible Function Image™.
2013 CML Microsystems Plc
Page 18
D/7161_FI-1.0/4
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