--- a/dac.pio	Mon Mar 29 13:54:55 2021 +1030
+++ b/dac.pio	Mon Mar 29 17:39:00 2021 +1030
@@ -1,48 +1,50 @@
 ;
-; Copyright (c) 2021 Raspberry Pi (Trading) Ltd.
-;
-; SPDX-License-Identifier: BSD-3-Clause
+; Copyright (c) 2021 Daniel O'Connor
 ;
 
 .program dac
 
-; Sample bits using an external clock, and push groups of bits into the RX FIFO.
-; - IN pin 0 is the data pin
-; - IN pin 1 is the clock pin
-; - Autopush is enabled, threshold 8
-;
-; This program samples data with each rising clock edge (like mode 0 or mode 3
-; SPI). The data is actually sampled one system clock cycle after the rising
-; edge is observed, so a clock ratio of at least input_clk < clk_sys / 6 is
-; recommended for good sampling alignment.
+.side_set 1
+; Clock DAC and write data from the FIFO
 
-    wait 0 pin 1
-    wait 1 pin 1
-    in pins, 1
+.wrap_target
+    pull side 1
+    out pins 8 side 0
+    nop side 1
+    out pins 8 side 0
+    nop side 1
+    out pins 8 side 0
+    nop side 1
+    out pins 8 side 0
+.wrap
 
 % c-sdk {
 static inline void dac_program_init(PIO pio, uint sm, uint offset, uint pin) {
     pio_sm_config c = dac_program_get_default_config(offset);
 
-    // Set the IN base pin to the provided `pin` parameter. This is the data
-    // pin, and the next-numbered GPIO is used as the clock pin.
-    sm_config_set_in_pins(&c, pin);
-    // Set the pin directions to input at the PIO
-    pio_sm_set_consecutive_pindirs(pio, sm, pin, 2, false);
+    // Set the OUT base pin to the provided `pin` parameter.
+    // First 8 pins are data, last is clock
+    sm_config_set_out_pins(&c, pin, 9);
+    // Set the pin directions to output at the PIO
+    pio_sm_set_consecutive_pindirs(pio, sm, pin, 9, true);
     // Connect these GPIOs to this PIO block
-    pio_gpio_init(pio, pin);
-    pio_gpio_init(pio, pin + 1);
+    for (int i = 0; i < 9; i++)
+        pio_gpio_init(pio, pin + i);
 
-    // Shifting to left matches the customary MSB-first ordering of SPI.
-    sm_config_set_in_shift(
+    sm_config_set_out_shift(
         &c,
-        false, // Shift-to-right = false (i.e. shift to left)
-        true,  // Autopush enabled
-        8      // Autopush threshold = 8
+        true,  // Shift-to-right
+        false, // Autopull enabled
+        8      // Autopull threshold (bits!)
     );
 
-    // We only receive, so disable the TX FIFO to make the RX FIFO deeper.
-    sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_RX);
+    // Configure clock as sideset pin
+    sm_config_set_sideset_pins(&c, pin + 7);
+
+    // We only send, so disable the RX FIFO to make the TX FIFO deeper.
+    sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
+
+//    sm_config_set_clkdiv(&c, 100);
 
     // Load our configuration, and start the program from the beginning
     pio_sm_init(pio, sm, offset, &c);