Fixes

Author: BenChung

deploy/src/icm42688.jl

@@ -257,20 +257,18 @@ function read_reg(imu::ICM42688, reg::Integer)
 end
 
 """
-    read_regs!(imu::ICM42688, reg::UInt8, dest::AbstractVector{UInt8}) -> Nothing
+    read_regs!(imu::ICM42688, reg::Integer, count::Int) -> Nothing
 
-Burst read multiple bytes starting from a register into dest.
+Burst read `count` bytes starting from a register.
+Data lands in `imu.rx_buf[2:count+1]` (index 1 is the discarded address echo).
 """
-function read_regs!(imu::ICM42688, reg::Integer, dest::AbstractVector{UInt8})
-    count = length(dest)
+function read_regs!(imu::ICM42688, reg::Integer, count::Int)
     n = count + 1  # 1 address byte + N data bytes
 
     imu.tx_buf[1] = UInt8(reg) | SPI_READ_FLAG
     fill!(@view(imu.tx_buf[2:n]), 0x00)
 
     SPI.transfer!(imu.device, @view(imu.tx_buf[1:n]), @view(imu.rx_buf[1:n]))
-
-    copyto!(dest, 1, imu.rx_buf, 2, count)
     return nothing
 end
 

deploy/src/shift_driver.jl

@@ -1,5 +1,39 @@
 using PIOLib
 
+function shift_register_program(; ser_pin::Integer, clk_pin::Integer, rclk_pin::Integer,
+                                  nbits::Integer, clkdiv::Real=1.0f0)
+    1 <= nbits <= 31 || error("nbits must be 1-31 (SET immediate is 5 bits, and 32 encodes as 0 in autopull threshold)")
+
+    prog = build_program([
+        WrapTarget(),
+        Mov{:none}(RegX(), RegY(); sideset=0),
+        Label(:bitloop),
+        Out(Pins(), 1; sideset=0),
+        Jmp{:x_dec}(:bitloop; sideset=1),
+        Set(Pins(), 1; sideset=0),
+        Set(Pins(), 0; sideset=0),
+        Wrap(),
+    ]; sideset_bits=1)
+
+    config = SMConfig(;
+        out_pins=(ser_pin, 1),
+        set_pins=(rclk_pin, 1),
+        sideset_pin_base=clk_pin,
+        sideset=(1, false, false),
+        out_shift=(true, true, nbits),
+        clkdiv=Float32(clkdiv),
+        wrap=(prog.wrap_target, prog.wrap),
+    )
+
+    prog, config
+end
+
+function setup_shift_register!(sm::StateMachine, nbits::Integer)
+    exec!(sm, Set(RegY(), nbits - 1))
+end
+
+shift_out!(sm::StateMachine, data::UInt32) = put!(sm, data)
+
 # --- Pin assignments ---
 const SER_PIN  = 26  # Serial data  (SER/DS)
 const CLK_PIN  = 19  # Shift clock  (SRCLK/SHCP)

deploy/src/spi.jl

@@ -333,12 +333,14 @@ Read into `dest` from the SPI device (half-duplex RX, TX sends zeros).
 """
 function Base.read!(dev::SPIDevice, dest::AbstractVector{UInt8})
     len = length(dest)
+    len > SPI_BUFFER_SIZE && error("read!: length $len exceeds buffer size $SPI_BUFFER_SIZE")
+
     fill!(@view(dev.scratch[1:len]), 0x00)
 
     xfer = SPIIocTransfer(UInt64(pointer(dev.scratch)), UInt64(pointer(dest)), UInt32(len), ZERO_XFER_TAIL...)
     unsafe_store!(Ptr{SPIIocTransfer}(pointer(dev.xfer_buf)), xfer)
 
-    do_xfer(dev, 1)
+    do_xfer(dev, 1, "read")
     return dest
 end
 
@@ -351,6 +353,8 @@ Useful for register reads: send command/address bytes in `tx`, receive response
 function write_then_read!(dev::SPIDevice, tx::AbstractVector{UInt8}, rx::AbstractVector{UInt8})
     tx_len = length(tx)
     rx_len = length(rx)
+    rx_len > SPI_BUFFER_SIZE && error("write_then_read!: rx length $rx_len exceeds buffer size $SPI_BUFFER_SIZE")
+
     xfer_ptr = Ptr{SPIIocTransfer}(pointer(dev.xfer_buf))
 
     # First transfer: write, keep CS asserted
@@ -362,7 +366,7 @@ function write_then_read!(dev::SPIDevice, tx::AbstractVector{UInt8}, rx::Abstrac
     unsafe_store!(xfer_ptr,
         SPIIocTransfer(UInt64(pointer(dev.scratch)), UInt64(pointer(rx)), UInt32(rx_len), ZERO_XFER_TAIL...), 2)
 
-    return do_xfer(dev, 2)
+    return do_xfer(dev, 2, "write_then_read")
 end
 
 end # module SPI