Read data out of AXI4 memory-mapped subordinates
data = readmemory(
size locations of data, starting from the address specified in
addr and then incrementing the address for each word. The function
casts the data to the
uint64 data type
(depending on the data size of the AXI manager IP). The address,
must refer to an AXI subordinate memory location controlled by the AXI manager IP on your
FPGA board. The
mem, manages the connection between MATLAB® and the AXI manager IP.
Access Memory on FPGA Board from MATLAB
This example shows how to read and write the memory locations on an Intel® FPGA board from MATLAB®.
Before you can use this example, you must have a design running on an FPGA board connected to the MATLAB host machine. The FPGA design must include an AXI manager IP that is customized for your FPGA vendor. The support package installation includes this IP. To include the IP in your project, see the Access FPGA External Memory Using AXI Manager example.
Create an AXI manager object. The object connects MATLAB with the FPGA board and confirms that the IP is present.
mem = aximanager('Intel')
aximanager with properties:
Vendor: 'Intel' JTAGCableName: 'auto'
Write 10 addresses and then read data from a single location. By default, these functions auto-increment the address for each word of data.
writememory(mem,140,[10:19]); rd_d = readmemory(mem,140,1)
Read data from 10 locations.
rd_d = readmemory(mem,140,10)
1x10 uint32 row vector
10 11 12 13 14 15 16 17 18 19
Read data 10 times from the same address by specifying that the AXI manager read all data from the same address (disabling auto-incrementation).
rd_d = readmemory(mem,140,10,'BurstType','Fixed')
1x10 uint32 row vector
10 10 10 10 10 10 10 10 10 10
Write data 10 times to the same address. In this case, the final value stored in address
writememory(mem,140,[20:29],'BurstType','Fixed'); rd_d = readmemory(mem,140,10)
1x10 uint32 row vector
29 11 12 13 14 15 16 17 18 19
Specify the address as a hexadecimal value. Specify for the function to cast the read data to a data type other than
writememory(mem,0x1c,[0:4:64]); rd_d = readmemory(mem,0x1c,16,'OutputDataType',numerictype(0,6,4))
Columns 1 through 10 0 0.2500 0.5000 0.7500 1.0000 1.2500 ... 1.5000 1.7500 2.0000 2.2500 Columns 11 through 16 2.5000 2.7500 3.0000 3.2500 3.5000 3.7500
DataTypeMode: Fixed-point: binary point scaling Signedness: Unsigned WordLength: 6 FractionLength: 4
When you no longer need to access the board, release the JTAG connection.
mem — Connection to AXI manager IP on FPGA board
Connection to the AXI manager IP on your FPGA board, specified as an
addr — Starting address for read operation
nonnegative integer multiple of 4 | nonnegative hexadecimal value multiple of 4
Starting address for the read operation, specified as a nonnegative integer multiple
of 4 or hexadecimal value multiple of 4. The function casts the address to the
uint64 data type, depending on the AXI
manager IP address width. The address must refer to an AXI subordinate memory location
controlled by the AXI manager IP on your FPGA board.
If the AXI manager IP data width is 32 bits, the memory is 4 bytes aligned, and addresses have 4-byte increments (
0x8). In this case,
0x1is an illegal address and emits an error.
If the AXI manager IP data width is 64 bits, the memory is 8 bytes aligned, and addresses have 8-byte increments (
0x10). In this case,
0x4are illegal and emit errors.
If the AXI manager IP data width is 32 bits and you set the
'Increment', the address has 4-byte increments.
If the AXI manager IP data width is 64 bits and you set the
'Increment', the address has 8-byte increments.
Do not use a 64-bit AXI manager for accessing 32-bit registers.
0xa4, specifies a starting address of
size — Number of memory locations to read
Number of memory locations to read, specified as a nonnegative integer. By default,
the function reads data from a contiguous address block, incrementing the address for
each operation. To disable address incrementation and read repeatedly from the same
location, set the
'BurstType' argument to
When you specify a large operation size, such as reading a block of DDR memory, the function automatically breaks the operation into multiple bursts, using the maximum supported burst size of 256 words.
5 specifies five contiguous memory
Specify optional pairs of arguments as
the argument name and
Value is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.
Before R2021a, use commas to separate each name and value, and enclose
Name in quotes.
'BurstType','Fixed' directs the AXI manager to read all data
from the same address.
BurstType — AXI4 burst type
'Increment' (default) |
AXI4 burst type, specified as one of these options:
'Increment'— The AXI manager reads a vector of data from contiguous memory locations, starting with the specified address.
'Fixed'— The AXI manager reads all data from the same address.
'Fixed' burst type is not supported for the PCI Express® interface. Use the
'Increment' burst type
OutputDataType — Data type assigned to read data
'uint32' (default) |
Data type assigned to the read data, specified as one of these options:
The function casts the data read out of the FPGA to the specified data type.
double is supported for 64-bit UDP connections only.
Introduced in R2017a