BMII

BMII is an open source general-purpose board controlled by USB and fully programmable with Migen.

It is based on an Altera Max V CPLD and a Cypress FX2LP.

Example: a Pulse-Width Modulation module

Define the RTL

from bmii import *

class PWMIOModule(IOModule):
    def __init__(self):
        IOModule.__init__(self, "PWM")

        self.cregs += CtrlReg("WIDTH", CtrlRegDir.RDWR)
        self.cregs += CtrlReg("COUNTER", CtrlRegDir.RDONLY)

        self.sync += self.cregs.COUNTER.eq(self.cregs.COUNTER + 1)

        self.iosignals += IOSignal("OUT", IOSignalDir.OUT)
        self.iosignals += IOSignal("NOUT", IOSignalDir.OUT)
        self.comb += self.iosignals.OUT.eq(self.cregs.COUNTER < self.cregs.WIDTH)
        self.comb += self.iosignals.NOUT.eq(~self.iosignals.OUT)

Define RTL testbench (optional)

from bmii.ioctl.testbench import *

class PWMTestCase(IOModuleTestCase(PWMIOModule())):
    def test_basic(self):
        def gen():
            yield self.tb.iomodule.cregs.WIDTH.eq(42)
            yield

            for i in range(41):
                self.assertEqual((yield self.tb.iomodule.iosignals.OUT), 1)
                yield

            for i in range(214):
                self.assertEqual((yield self.tb.iomodule.iosignals.OUT), 0)
                yield

            self.assertEqual((yield self.tb.iomodule.iosignals.OUT), 1)

        self.run_with(gen())

Connect the PWM to physical pins

class PWM(BMIIModule):
    def __init__(self):
        BMIIModule.__init__(self, PWMIOModule(), PWMTestCase)

    @classmethod
    def default(cls, bmii):
        pwm = cls()
        bmii.add_module(pwm)

        bmii.ioctl.sb.pins.LED0 += pwm.iomodule.iosignals.OUT
        bmii.ioctl.sb.pins.LED1 += pwm.iomodule.iosignals.NOUT

        bmii.ioctl.sb.pins.IO10 += pwm.iomodule.iosignals.OUT

        return pwm

bmii_modules = [PWM]

Build the design

$ bmii -v -m pwm.py build all
[INFO] ixo.de USB JTAG firmware built
[INFO] USB controller firmware built
[INFO] IO controller design built

Program the board

$ bmii -v -m pwm.py program all
[INFO] [STAGE 1] Loading CPLD programmer firmware
[INFO] ixo.de USB JTAG firmware loaded
[INFO] [STAGE 2] Loading CPLD design
[INFO] Probe: USB-JTAG-BM [2-2]
[INFO] Model: 5M570Z/EPM570Z
[INFO] IDCODE: 020A60DD
[INFO] IO Controller configured
[INFO] [STAGE 3] Flashing EEPROM
[INFO] USB controller firmware flashed
[INFO] [STAGE 4] Loading USB firmware
[INFO] USB controller firmware loaded
[INFO] Found device (002:017)
[INFO] IDCODE: A5
[INFO] Device fully tested

Set pulse width

$ bmii -v -m pwm.py set PWM WIDTH 100

Simulate the PWM module

$ bmii -v -m pwm.py simulate PWM
[INFO] Simulating PWM
..
----------------------------------------------------------------------
Ran 2 tests in 0.156s

OK

Requirements

• Migen
• Altera Quartus, with Max V support
• PyUSB
• fxload
• sdcc
• ninja

Getting a BMII

For now, this board is handmade and therefore not yet distributed. However, If you are interested in getting your own BMII but are not brave enough to solder it yourself, just sent me a short email.

If enough people manifest their interests to order a board, a small batch will be manufactured. The estimated cost would be approximately 50 euros per unit.