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---
--- I2C
---
STMP.i2c = {}
local h = HELP:get_topic("STMP"):create_topic("i2c")
h:add("The STMP.clkctrl table handles the i2c device for all STMPs.")
function STMP.i2c.init()
HW.I2C.CTRL0.SFTRST.set()
STMP.pinctrl.i2c.setup()
STMP.i2c.reset()
STMP.i2c.set_speed(true)
end
function STMP.i2c.reset()
HW.I2C.CTRL0.SFTRST.set()
HW.I2C.CTRL0.SFTRST.clr()
HW.I2C.CTRL0.CLKGATE.clr()
-- errata for IMX233
if STMP.is_imx233() then
HW.I2C.CTRL1.ACK_MODE.set();
end
end
function STMP.i2c.set_speed(fast)
if fast then
-- Fast-mode @ 400K
HW.I2C.TIMING0.write(0x000F0007) -- tHIGH=0.6us, read at 0.3us
HW.I2C.TIMING1.write(0x001F000F) -- tLOW=1.3us, write at 0.6us
HW.I2C.TIMING2.write(0x0015000D)
else
-- Slow-mode @ 100K
HW.I2C.TIMING0.write(0x00780030)
HW.I2C.TIMING1.write(0x00800030)
HW.I2C.TIMING2.write(0x00300030)
end
end
function STMP.i2c.transmit(slave_addr, buffer, send_stop)
local data = { slave_addr }
for i, v in ipairs(buffer) do
table.insert(data, v)
end
if #data > 4 then
error("PIO mode cannot send more than 4 bytes at once")
end
HW.I2C.CTRL0.MASTER_MODE.set()
HW.I2C.CTRL0.PIO_MODE.set()
HW.I2C.CTRL0.PRE_SEND_START.set()
HW.I2C.CTRL0.POST_SEND_STOP.write(send_stop and 1 or 0)
HW.I2C.CTRL0.DIRECTION.set()
HW.I2C.CTRL0.SEND_NAK_ON_LAST.clr()
HW.I2C.CTRL0.XFER_COUNT.write(#data)
local v = 0
for i,d in ipairs(data) do
v = v + bit32.lshift(d, (i - 1) * 8)
end
HW.I2C.DATA.write(v)
HW.I2C.CTRL1.clr(0xffff)
HW.I2C.CTRL0.RUN.set()
while HW.I2C.CTRL0.RUN.read() == 1 do
end
if HW.I2C.CTRL1.NO_SLAVE_ACK_IRQ.read() == 1 then
if STMP.is_imx233() then
HW.I2C.CTRL1.CLR_GOT_A_NAK.set()
end
STMP.i2c.reset()
return false
end
if HW.I2C.CTRL1.EARLY_TERM_IRQ.read() == 1 or HW.I2C.CTRL1.MASTER_LOSS_IRQ.read() == 1 then
return false
else
return true
end
end
function STMP.i2c.receive(slave_addr, length)
if length > 4 then
error("PIO mode cannot receive mode than 4 bytes at once")
end
-- send address
HW.I2C.CTRL0.RETAIN_CLOCK.set()
STMP.i2c.transmit(bit32.bor(slave_addr, 1), {}, false, true)
HW.I2C.CTRL0.DIRECTION.clr()
HW.I2C.CTRL0.XFER_COUNT.write(length)
HW.I2C.CTRL0.SEND_NAK_ON_LAST.set()
HW.I2C.CTRL0.POST_SEND_STOP.set()
HW.I2C.CTRL0.RETAIN_CLOCK.clr()
HW.I2C.CTRL0.RUN.set()
while HW.I2C.CTRL0.RUN.read() == 1 do
end
if HW.I2C.CTRL1.NO_SLAVE_ACK_IRQ.read() == 1 then
if STMP.is_imx233() then
HW.I2C.CTRL1.CLR_GOT_A_NAK.set()
end
STMP.i2c.reset()
return nil
end
if HW.I2C.CTRL1.EARLY_TERM_IRQ.read() == 1 or HW.I2C.CTRL1.MASTER_LOSS_IRQ.read() == 1 then
return nil
else
local data = HW.I2C.DATA.read()
local res = {}
for i = 0, length - 1 do
table.insert(res, bit32.band(0xff, bit32.rshift(data, 8 * i)))
end
return res
end
end
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