pulsar_adc: add split transfer functionality

add a parameter, SPLIT_TRANSFER_SIZE, to enable and control split transfers. If SPLIT_TRANSFER_SIZE is set to 0 (default), the project behaves as usual (no split transfers). Otherwise, an asymetric fifo is used to stitch together 2 transfers before sending them to the DMA, SPLIT_TRANSFER_SIZE being used to indicate the size of each transfer in the split. Signed-off-by: Laez Barbosa <[email protected]>
analogdevicesinc · Oct 4, 2024 · a99fac3 · a99fac3
1 parent 1dd8efc
commit a99fac3
Show file tree

Hide file tree

Showing 4 changed files with 41 additions and 1 deletion.
diff --git a/docs/projects/pulsar_adc/index.rst b/docs/projects/pulsar_adc/index.rst
@@ -185,6 +185,15 @@ These modes are selected using the ``SPI_OP_MODE`` parameter:
 
    The SPI_OP_MODE parameter must only be used for the FMC variant.
 
+Some ADCs like the AD7944 allow for split transfers, which require samples to be
+assembled out of two SPI Engine transfer reads from the ADC. This is enabled by
+the ``SPLIT_TRANSFER_SIZE`` parameter. If 0, split transfers are disabled. For
+values greater than 0, it determines the size of each of the two transfers that
+make up the split transfer.
+
+*  0 - for no split transfers (default)
+*  N - for N>0, selects the size of each transfer that make up the sample
+
 CPU/Memory interconnects addresses
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

diff --git a/projects/pulsar_adc/common/pulsar_adc_bd.tcl b/projects/pulsar_adc/common/pulsar_adc_bd.tcl
@@ -15,6 +15,8 @@ set num_sdo       1
 set sdi_delay     1
 set echo_sclk     0
 
+set SPLIT_TRANSFER_SIZE [get_env_param SPLIT_TRANSFER_SIZE 0]
+
 set hier_spi_engine spi_pulsar_adc
 
 spi_engine_create $hier_spi_engine $data_width $async_spi_clk $num_cs $num_sdi $num_sdo $sdi_delay $echo_sclk
@@ -40,6 +42,24 @@ ad_ip_parameter axi_pulsar_adc_dma CONFIG.DMA_2D_TRANSFER 0
 ad_ip_parameter axi_pulsar_adc_dma CONFIG.DMA_DATA_WIDTH_SRC $data_width
 ad_ip_parameter axi_pulsar_adc_dma CONFIG.DMA_DATA_WIDTH_DEST 64
 
+if {$SPLIT_TRANSFER_SIZE != 0} {
+    ad_ip_instance util_axis_fifo_asym rx_asym_fifo
+    ad_ip_parameter rx_asym_fifo CONFIG.ASYNC_CLK 0
+    ad_ip_parameter rx_asym_fifo CONFIG.S_DATA_WIDTH $SPLIT_TRANSFER_SIZE
+    ad_ip_parameter rx_asym_fifo CONFIG.S_ADDRESS_WIDTH 3
+    ad_ip_parameter rx_asym_fifo CONFIG.M_DATA_WIDTH [expr {2*$SPLIT_TRANSFER_SIZE}]
+    ad_ip_parameter rx_asym_fifo CONFIG.M_AXIS_REGISTERED 1
+    ad_ip_parameter rx_asym_fifo CONFIG.ALMOST_EMPTY_THRESHOLD 2
+    ad_ip_parameter rx_asym_fifo CONFIG.ALMOST_FULL_THRESHOLD 6
+    ad_ip_parameter rx_asym_fifo CONFIG.TLAST_EN 0
+    ad_ip_parameter rx_asym_fifo CONFIG.TKEEP_EN 0
+
+    ad_connect spi_clk rx_asym_fifo/s_axis_aclk
+    ad_connect $hier_spi_engine/${hier_spi_engine}_axi_regmap/spi_resetn rx_asym_fifo/s_axis_aresetn
+    ad_connect spi_clk rx_asym_fifo/m_axis_aclk
+    ad_connect $hier_spi_engine/${hier_spi_engine}_axi_regmap/spi_resetn rx_asym_fifo/m_axis_aresetn
+}
+
 ad_connect $sys_cpu_clk spi_clkgen/clk
 ad_connect spi_clk spi_clkgen/clk_0
 
@@ -48,7 +68,12 @@ ad_connect $sys_cpu_clk pulsar_adc_trigger_gen/s_axi_aclk
 ad_connect sys_cpu_resetn pulsar_adc_trigger_gen/s_axi_aresetn
 ad_connect pulsar_adc_trigger_gen/pwm_0 $hier_spi_engine/trigger
 
-ad_connect axi_pulsar_adc_dma/s_axis $hier_spi_engine/M_AXIS_SAMPLE
+if {$SPLIT_TRANSFER_SIZE != 0} {
+    ad_connect rx_asym_fifo/s_axis $hier_spi_engine/M_AXIS_SAMPLE
+    ad_connect axi_pulsar_adc_dma/s_axis rx_asym_fifo/m_axis
+} else {
+    ad_connect axi_pulsar_adc_dma/s_axis $hier_spi_engine/M_AXIS_SAMPLE
+}
 ad_connect $hier_spi_engine/m_spi pulsar_adc_spi
 
 ad_connect $sys_cpu_clk $hier_spi_engine/clk

diff --git a/projects/pulsar_adc/zed/Makefile b/projects/pulsar_adc/zed/Makefile
@@ -31,5 +31,6 @@ LIB_DEPS += spi_engine/spi_engine_interconnect
 LIB_DEPS += spi_engine/spi_engine_offload
 LIB_DEPS += sysid_rom
 LIB_DEPS += util_i2c_mixer
+LIB_DEPS += util_axis_fifo_asym
 
 include ../../scripts/project-xilinx.mk
diff --git a/projects/pulsar_adc/zed/system_project.tcl b/projects/pulsar_adc/zed/system_project.tcl
@@ -25,6 +25,7 @@ source $ad_hdl_dir/projects/scripts/adi_board.tcl
 ##
 set FMC_N_PMOD [get_env_param FMC_N_PMOD 1]
 set SPI_OP_MODE [get_env_param SPI_OP_MODE 0]
+set SPLIT_TRANSFER_SIZE [get_env_param SPLIT_TRANSFER_SIZE 0]
 
 adi_project pulsar_adc_pmdz_zed 0 [list \
   FMC_N_PMOD    [get_env_param FMC_N_PMOD  1] \
@@ -56,5 +57,9 @@ if {$FMC_N_PMOD == 0} {
   return -code error [format "ERROR: Invalid eval board type! ..."]
 }
 
+if {$SPLIT_TRANSFER_SIZE < 0 || ![string is integer $SPLIT_TRANSFER_SIZE]} {
+  return -code error [format "ERROR: Illegal value for SPLIT_TRANSFER_SIZE ..."]
+}
+
 adi_project_run pulsar_adc_pmdz_zed