75 lines
2.1 KiB
Lua
75 lines
2.1 KiB
Lua
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---
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--- I2C
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---
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STMP.i2c = {}
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local h = HELP:get_topic("STMP"):create_topic("i2c")
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h:add("The STMP.clkctrl table handles the i2c device for all STMPs.")
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function STMP.i2c.init()
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HW.I2C.CTRL0.SFTRST.set()
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STMP.pinctrl.pin(0, 30).muxsel("MAIN")
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STMP.pinctrl.pin(0, 30).pull(true)
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STMP.pinctrl.pin(0, 31).muxsel("MAIN")
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STMP.pinctrl.pin(0, 31).pull(true)
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STMP.i2c.reset()
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STMP.i2c.set_speed(true)
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end
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function STMP.i2c.reset()
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HW.I2C.CTRL0.SFTRST.set()
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HW.I2C.CTRL0.SFTRST.clr()
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HW.I2C.CTRL0.CLKGATE.clr()
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-- errata for IMX233
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HW.I2C.CTRL1.ACK_MODE.set();
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end
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function STMP.i2c.set_speed(fast)
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if fast then
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-- Fast-mode @ 400K
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HW.I2C.TIMING0.write(0x000F0007) -- tHIGH=0.6us, read at 0.3us
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HW.I2C.TIMING1.write(0x001F000F) -- tLOW=1.3us, write at 0.6us
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HW.I2C.TIMING2.write(0x0015000D)
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else
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-- Slow-mode @ 100K
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HW.I2C.TIMING0.write(0x00780030)
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HW.I2C.TIMING1.write(0x00800030)
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HW.I2C.TIMING2.write(0x00300030)
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end
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end
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function STMP.i2c.transmit(slave_addr, buffer, send_stop)
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local data = { slave_addr }
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for i, v in ipairs(buffer) do
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table.insert(data, v)
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end
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if #data > 4 then
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error("PIO mode cannot send more than 4 bytes at once")
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end
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HW.I2C.CTRL0.MASTER_MODE.set()
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HW.I2C.CTRL0.PIO_MODE.set()
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HW.I2C.CTRL0.PRE_SEND_START.set()
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HW.I2C.CTRL0.POST_SEND_STOP.write(send_stop and 1 or 0)
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HW.I2C.CTRL0.DIRECTION.set()
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HW.I2C.CTRL0.SEND_NAK_ON_LAST.clr()
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HW.I2C.CTRL0.XFER_COUNT.write(#data)
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local v = 0
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for i,d in ipairs(data) do
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v = v + bit32.lshift(d, (i - 1) * 8)
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end
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HW.I2C.DATA.write(v)
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HW.I2C.CTRL1.clr(0xffff)
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HW.I2C.CTRL0.RUN.set()
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while HW.I2C.CTRL0.RUN.read() == 1 do
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end
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if HW.I2C.CTRL1.NO_SLAVE_ACK_IRQ.read() == 1 then
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HW.I2C.CTRL1.CLR_GOT_A_NAK.set()
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STMP.i2c.reset()
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return false
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end
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if HW.I2C.CTRL1.EARLY_TERM_IRQ.read() == 1 or HW.I2C.CTRL1.MASTER_LOSS_IRQ.read() == 1 then
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return false
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else
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return true
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end
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end
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